Never Use This Gas In Your Car!

[@EngineeringExplained]

**Some additional important information!** Modern turbocharged engines are based on absolute pressure, so they will attempt to match the cylinder pressure when at elevation to that of sea-level by providing more boost (with a lower baseline atmospheric pressure). Because you have the same amount of air in the cylinder, but are using a lower grade fuel, you can run into knock issues - hence, this is especially important to avoid doing with modern turbo engines. That said, even the engines tested from 1987 showed that the Octane # drop requirement was significantly less for "modern" engines (again, 1987), regardless of induction method, so this is not an exclusive problem to turbo engines. Does Europe have higher octane fuel? No, explained here - kzbin.info/www/bejne/sJeQgIyOoc19n9U Is premium gas actually worth it? Not always, explained here - kzbin.info/www/bejne/mqmkgqCgaLVrrtU Octane vs Cetane - what's the difference? Explained here - kzbin.info/www/bejne/haK5Zn9tZZKAi6c Is Ethanol bad for your engine? Explained here - kzbin.info/www/bejne/d4WqhHWfZtB1opI *Important Edit:* E85 gas ≠ 85 Octane gas. E85 is 85% ethanol and has a very high octane rating (100+). 85 Octane gas is at max (if sold as regular gas) 10% ethanol and has an octane rating of 85. Do not use E85 if your car is not made for it (generally these cars are labeled as FlexFuel).

[@proximusadiemus8731]

Great video and explanation like always... BUT, can you make a part 2 where you will talk thru maybe potential problem with that same F150 if I import that vehicle in Europe and put in it 100 octane fuel ⛽ 😁 🤔

[@brettdavis9575]

Hi Jason, talk to us about your thoughts on this new Unleaded88/E15 that's being advertised.

[@ctbrahmstedt]

In Colorado, where I live, the highest grade gas you can get is 91. If I were lucky enough to have a vehicle that requires 93, but only put in 91, would the vehicle knock it's brains out, or can most modern vehicles cope and retard the timing to keep the cylinder pressures out of the no-no zone under high load?

[@stephenjacks8196]

Seems kinda IGNORANT because almost all newer vehicles are fuel injected. Octane rating is for carbuerated engines. Preignition occurs when air and gasoline are premixed. By the way our lab used to test gasoline, today's "85 octane" is usually 10 points less using ASTM standard test engine. EPA certified (required in the US) engine delays injection and ignition are degrees past top dead center. Modern cars are not allowed to be designed for peak performance as that generates Nitrogen Oxides (NOx).

[@borysnijinski331]

@@stephenjacks8196 woah, dude…not even close. You have no clue…what you wrote is way off base.

[@ShortHax]

Jason’s videos need to be played on repeat at the DMVs

[@EngineeringExplained]

As if the experience couldn't get any *more* boring! 😂

[@HeartTribe]

@@EngineeringExplained oh man, if that were the case you'd catch me there on time everytime I needed to be there lol.

[@youkofoxy]

@@EngineeringExplained I kinda have to agree, despite your efforts you don't have enough content to avoid repetition during the wait at DMV.

[@mjc0961]

@@CedroCron If gas pumps started playing EE videos instead of ads, I'd be so much happier about going to the gas station.

[@ts31966]

@@EngineeringExplained hahahahaha, boring depends on your perspective. A sixteen year old girl that daddy buys all her cars. Boring!!!!!! A guy who has no financial help and knows how hard his local car mechanic is screwing him....Engineering Explained is the best channel EVER!!!

[@KF1]

within literally 2 min 10,000 people showed up to learn from a lecture in front of a white board. Doin' something right, man.

[@calholli]

He has 3 million subs. lol.. 10k is nothing

[@AliasHSW]

This goes to shows high tech is not (always) the best tech.

[@strangeclouds7]

@@calholli Subs don't always translate to views

[@dielaughing73]

@@calholli that's exactly their point

[@boozecruiser]

Higher education is out of reach to normal Americans who don't want to spend their live as a debt slave

[@MadeNewOmaha]

I wish I was still teaching high school automotive repair classes. This video would be perfect for explaining Octane ratings and how they work. Thanks for making awesome content!

[@EngineeringExplained]

Thanks for the kind words!

[@taylorc2542]

Dude, you're a teacher, this is something you should be able to explain yourself. It'll hit much harder coming from you.

[@DirtyFiST69]

@@taylorc2542 just cus he's a teacher doesn't mean he can't use learning aides, different things work for different people. A video explaining it slightly differently + visualization in addition to his way of showing it might be beneficial to certain students. I know it would help me for example. Throughout college I found myself constantly looking for multiple examples of things on KZbin or forums or Google because sometimes however the teachers explained it didn't cut it for my brain, other times I just needed a reiteration or I missed something.

[@evanc6110]

@@DirtyFiST69 p

[@cjaydok]

@@evanc6110 p

[@jaslionel7273]

Good to know. Thanks for keeping things in perspective. I used to own a '98 Taurus (not an HO but the "fleet car" kind) that "pinged" terribly when accelerating, so I started using premium gas to try and prevent detonation. So when I tried to explain to a service rep at the dealership he told me that I was making the engine pinging worse by using premium gas instead of regular 87 octane. Go figure. It just shows that a lot of people have difficulty understanding how octane in gasoline effects engine performance.

[@roboticvenom1935]

yeah that's silly, ona. 98 taurus it shouldn't have much of an effect, definitely wont hurt it by putting better fuel, but on newer cars that are much more advanced, and ESPECIALLY if tehy're turbocharged, putting 91 or 93 is better for the engine and you'll likey pick up some horsepower, also depends on the motor. mazda's 2.5 turbo can be used with 87 fuel and makes 227horse and 251 horse on 93, and more torque

[@mplslawnguy3389]

@@roboticvenom1935 "Premium" fuel isn't "better" fuel.

[@sategllib2191]

​@mplslawnguy not any cleaner. But for performance it does

[@tomasprieto9746]

That makes no sense, higher octane absolutely has higher knock resistance.

[@imzjustplayin]

Ignore the people that say the Premium fuel didn't help. If you think it helped, it likely did help. I've seen many instances of different octane fuels either helping or hurting the vehicle. One person I know always put premium in vehicles so when they had an eagle talon, it ran terribly with the Premium fuel and I told them they needed to use regular with this car and they did and it ran much better. It's always vehicle specific so I think there is no issue with trying different octane fuel and monitoring its effects.

[@mmytacist]

2 years later and this is still useful. Driving x-country from Calif to Florida. Refueled my 2024 Honda somewhere before Albuquerque and wasn't using my brain when I picked the fuel button at the far left. As I was refueling I saw it was 85 octane. And 10% ethanol. Drove on across I-40 for about 300 miles and filled up again with normal gas in Amarillo. Never heard knocks, not towing anything, keep it under 80. But I kept wondering about that 85 octane... until now!

[@SaraMorgan-ym6ue]

gas that can kill your car and it's sold to do that one.🤣🤣🤣🤣🤣 why can they do this one but not sell renewable fuels alcohol based to save the environment?🤔

[@mikebradford7780]

​@@SaraMorgan-ym6ueClueless lie.

[@artosbear]

So it was fine you mean? Wow amazing it was fine. Because it's fine. You aren't driving a damn motorcycle

Based on your mistake described, if you where at a Chevron station you would have filled up with supreme. Then that would open up a whole other can of deception

[@SaraMorgan-ym6ue]

and Drink it like water💀💀

[@noremorse6898]

I live in the Denver area and have always used 87 octane in my cars, which is labeled midgrade here. What really ticks me off is that over time the price gap between 85 and 87 has risen from 10 cents to 30 cents per gallon. I can’t believe there’s any justification for that, when I can drive to a neighboring low altitude state and buy 87 octane for less than what 85 costs in Colorado.

[@jerwatson79]

We are dealing with $1.54 per litre here. You guys have it lucky down there

[@mikej238]

Liberal state taxes

[@squrrll]

​@@mikej238nonsense. Utah charges just as much as Denver, and we default to 85 too.

[@jamesyates5191]

That is the best explanation of 85 vs 87 octane I’ve ever seen. I drive a 2022 Newmar motor home with Ford V8 and never put 85 octane in it. Thank you

[@Kacpa2]

87 is already very bad especially for turbo charged cars, only because of direct injection and tuning tricks it barely scraping by without knock on 87 and at ultimate cost to power output and efficiency. 85 is is just for most lazy tuned rich running naturally aspirated engines with very low compression.

[@Sloth-j1m]

I used to haul fuel and 87 is just 85 with a 1 percent blend of ethanol all you need is some additive to raise the octane rating

[@Davido50]

​@@Sloth-j1m Good pts.

[@DJR5280]

I live in Denver. 85 is at every station here. The reason they use it is because they make more $$$$. They can upcharge that much more for 87 or 91. If I'm in Phoenix 87 is the minimum octane rating at pumps and it's cheaper than our 85 in Denver. Just sad.

[@WorasLT]

Whereas back in Lithuanian - 95 is minimum and everywhere, 98 is common too, but less likely.

[@UncleKennysPlace]

@@WorasLT But that's not directly comparable to USA's AKI, or we'd be using it in aeroplanes here (if it has no lead.)

[@andresamson8859]

dude don't come in Quebec, our price is equivalent to 5,50$/gal for 87octone. After US/CAD conversion, it's still above 4.30$/gal.

[@MrKurbek]

Hello fellow Denverite!

[@mowcowbell]

@@Guy_de_Loimbard ding ding! Correct answer! 85 octane is even available in lower altitude areas like Amarillo, TX.

[@stevet6676]

I live in Colorado, and we have 85 octane everywhere. I own a 2019 Subaru (non turbo) and the owners manual states something similar. The oil companies / gas stations often rip off customers by charging more for 87 octane than they should. When I fill up, I fill half the tank with 85, then the next half with 91. I end up with a tank of 88 for the same or less cost than 87. 85 should be banned.

[@crissd8283]

I really think banning it is extreme. If the people stop buying it then stations will stop selling it. I put it in any non turbo charged vehicle when at elevation. Modern cars have knock sensors and will protect themselves.

[@andresperez8382]

1:22 I think you should say that octane is the fuel’s resistance to pre-detonation or pre-ignition instead of knock since this is what causes knock and it isn’t knock itself

[@Fausto_4841]

Yeah, I was really surprised to hear him say that’s what octane means. Specially so early on in the video. Made me wonder what else he was going to get slightly wrong that I wouldn’t catch.

[@JaydenET]

Other way around Knock, detonation, pinging, etc is when spark timing is too advanced and cylinder pressures get so high from that spark event that some of the mixture combusts from pressure rather than the flame front. Pre-ignition, is typically caused by hotspots, caused by carbon buildup, lean afr, or detonation. The mixture ignites before the spark event occurs, the engine is basically dieseling. Pre meaning pre-spark event

[@Discretesignals]

@@JaydenET Knock occurs because of multiple flame fronts occurring at the same time inside a combustion chamber. Detonation happens after the spark event and can result in knock. Preignition just means the fuel/air mixture ignited prior to spark the event. Dieseling or engine run on is basically auto ignition of an fuel/air mixture after the ignition system is turned off. Dieseling was pretty much eliminated by fuel injection and carbs with anti dieseling solenoids.

[@dukecraig2402]

There's nothing wrong with what he said, he's using the word knock as a blanket term and there's no need splitting hairs and turning this into a video mostly about the different types of that phenomenon when it's about the dangers of using high altitude low octane fuel in something with a turbo, stay on point here.

[@joehoover7711]

@@Fausto_4841 he neglects to differentiate 85unleaded vs e85 e85 has an octane of 100

[@ReivecS]

This video was great for explaining a confusion I had when I was visiting Utah with a rented car and had to fill up. I immediately noticed the numbers on the octane were different and I had no idea why that was the case. Thanks for informing me as to how this came to be.

[@raven4k998]

ssooo 87 good 86 and below is bad unless your driving a car from the stone age got it🤣🤣🤣🤣🤣

[@buffuniballer]

Since it was a rental, it was okay to put 85 AKI fuel in the vehicle.

[@DarkAttack14]

​@@raven4k998more like if you're in Denver a mile above sea level you want lower octane ;)

[@haqitman]

Thank you Jason for addressing this! Back in the 70s and 80s in the Intermountain West, regular leaded was 87 and unleaded was 85, even if you lived at a relatively low elevation like 2000 feet. You had no other unleaded fuel option and 85 octane unleaded was some 5% to 10% more expensive than leaded regular. What's unfortunate is that most people back then knew the dangers of lead and would have paid the same or a little more for an equal octane unleaded but it just wasn't available. Instead it was very common for people to yank out the catalytic converter so they could simply run better fuel because, in reality, car performance suffered significantly when the timing was backed off enough to be able to run on that 85 octane garbage no matter what elevation you lived at. It wasn't until the late 80s that unleaded premium became available and you could get decent performance again. Fuel in the US is relatively cheap, but it's a substandard product. If octane ratings were required to be in the mid 90s, we could get away with engines that are smaller and more fuel efficient yet still make the same power via higher compression ratios or forced induction.

[@brolohalflemming7042]

Sadly, it seems to be politics, along with lobbying from agriculture. So E85 can be promoted as a 'green' fuel because it's adulterated with ethanol made from corn. If it reduces efficiency and damages your car, well, that's your problem. But the suppliers are saving the planet.

[@haqitman]

@@brolohalflemming7042 I don't think we're talking about the same thing. E85 is very high octane fuel, something like 100 plus. When unleaded came out in the mid 70s, it was 85 octane in our area and cars had a hard time running on it and there was no alternative.

[@logainfalsedragon3587]

@@brolohalflemming7042 E-85 is nothing like 85 octane gasoline. E-85 is 51-85% ethanol alcohol, aka drinking alcohol, depending on your location in the US. It's cut with gasoline to aid with cold weather starting. The colder your location the more dino gas it has. E-85's octane rating (100-105) exceeds most offerings at the pump. It's the poor man's nitromethane, as long as you can remove the gasoline and water it absorbed. Is it terrible fuel mileage, compared to dino gas? Yes. Does E-85 damage the fuel system? Yes, if you don't replace the components that get damaged over time for ones that aren't affected by ethanol, but to sit there and compare it to a substandard fuel, like 85 octane, please do some research before you let your fingers do your talking

[@electric7487]

@@brolohalflemming7042 Sugarcane and beets are much more efficient sources of bioethanol than corn anyways. It's been demonstrated countless times that corn ethanol's net energy balance is a _big negative_ but the only reason we do it is because of corn lobbyists.

[@haqitman]

@Lassi Kinnunen 81 There's a big difference between 85 and 87 octane. Back in the day I'd have to back the ignition timing off 4 degrees to run on 85, else the engine would ping and clatter badly, power and mileage dropped.

[@damon0559]

For what its worth I worked in the service department for a chrysler/jeep/ram dealer in colorado (where everyone uses 85) for 6 years and never once had, or heard of, a knock/pre-detonation issue on a non-turbo charged vehicle (most of which specify 91/premium anyway) not related to mechanical failure. I think if the vehicle is staying at altitude without forced induction its unlikely to have any problem. That being said the use of 85 in a turbo charged vehicle was a common problem and I would be surprised any manufacturer would recommend 87 instead of 91 for a turbocharged engine. I do think there is confusion by people refueling at high altitude and then returning to lower, and I have heard people (incorrectly) claim that 85 is the same as 87 sold at lower altitude and that the altitude makes them perform differently thus the change in labeling.

[@Anvarynn]

It's hilarious you said basically everything he did in the last quarter of the video...

[@PARULES2]

@@Anvarynn i know right if only he watched the whole video lol could have saved him the time typing up his message lmfao

[@Sumanitu]

Both of the commenters to this thead seem to lack some reading comprehension skills. Specifically the OP's second paragraph expressed concern that people might be told that octane ratings might be based on different altitudes, vs what is actually in the gas.

[@Anvarynn]

@@Sumanitu No I'm very capable of reading, hero

[@MrBenHaynes]

KIA/Hyundai turbocharged vehicles in Australia are recommended to run on AKI87 (Research Octane Number 91). Most small capacity turbo petrol vehicles are European in origin and are tuned to run on AKI89 (RON95) at a bare minimum. A large proportion of Aussies use a higher rated fuel than manufacturer recommendation (wasting money) in the belief that it causes less wear and has cleaning properties.

[@milinddixit6583]

At this point in the UK, I'd put anything in my car as long as it makes it move.

[@rjung_ch]

Empty shelves are also common, looks like pictures from the old Ussr days mate. Hope you all get this solved sooner than later

[@davidellis1355]

Also from the UK, I'd get used to walking

[@35RSkyline]

:( sadly I understand your pain.

[@NB-kh5jf]

Wtf is happening there, I saw some pictures but don't know the context.?

[@loickl]

@@NB-kh5jf lack of truck drivers, lack of stock, brexit impact. A secret report from an oil company has been published that stocks are low and created a big panick buy that made it worst. That is what i understood of it.

[@samuelhulin180]

I've used 85 octane in every car I have ever owned up here in Colorado. Never had a knock issue. Some cars get slightly better fuel economy using mid-grade, but I've driven for hundreds of thousands of miles across multiple decades and this has never been an issue. I don't come down from this elevation very often so maybe life is different for people at sea level, but 85 is just fine up here.

[@jeffhidalgo6037]

I don't like how gas stations attempt to market 93 octane as better for your engine when the truth is that you want the lowest possible octane that doesn't cause knock since a higher octane will mean less of the fuel is ignited. You'll get better gas mileage, more power and better emissions with the lower octane as long as there's no early detonation (knock) occurring. Great video to help people understand!

[@EngineeringExplained]

Careful! It's often not needed, but higher octane doesn't mean you'll ignite less of the fuel. It will all still burn, it's just excessive in that you never get near knock, so you're paying for and advantage you don't see. Explained in more detail in the pinned comment.

[@kc9scott]

I believe the ignition / flame propagation happens more slowly with higher-octane fuel. If you use excessively-high octane fuel without correspondingly advancing the timing, it will all ignite, but if the combustion is slower, it could happen late enough in the cycle that you won’t get as much crankshaft torque, and some of it might still be burning when the exhaust valve opens.

[@TechnicalLee]

This isn't really true anymore, modern engines use timing adaptability to adjust to the octane of the fuel being used to extract the maximum amount of power and efficiency (they run just under knock threshold). For example, Ford EcoBoost engines only require 87 octane minimum, but will develop more horsepower and efficiency on 93 because the timing can adjust to take advantage of the higher octane. Horsepower ratings are also done with 93 octane not 87. What you said might have been more correct 15+ years ago before engines had the technology to adjust to knock threshold.

[@DragonKnightX12]

The only recommendation that has ever mattered is the one from the manufacturer. Yea it's a waste on a something like a Honda Civic, but just Lee said. If a Engines recommends higher grade fuel, you're going to lose all around efficiency by going lower. Less power, worse gas millage, and honestly there's always gonna be a higher potential for knock. Specially depending on the specific engine. I always try to stick with the recommended fuel.

[@-nightraider-1169]

Not if your car is tuned to run best on higher octane gas. I get more gas mileage, more power and a much smoother driving car on higher octane gas then regular.

[@eightballsidepocket]

Useless Trivia: The footage of the truck towing the travel trailer is outside Yarnell, AZ. Great little piece of highway. Got my last speeding ticket in my GTI on that two lane section. One reason why I am an off-roader now; fewer traffic laws. LOL

[@dobiedude7479]

I used to ride my sport bike up that hill. What a blast

[@genemasters4986]

I know that area of highway 71 well... speeding tickets are quite frequent there... wide open road heading Southeast to junction with 93.

[@be5952]

@Jesse Ansell --- May seem "useless", but I still like reading about people's little corners of the world. Thanks for that :)

[@roguethrax]

Ah yeah that's a super common route we take to cruise to flagstaff. We hit it super early in the morning when there isn't any traffic. These days I usually stick to the track though!

[@mikebell2750]

85 octane was fine back 70 years ago when some of the old cars had 7:1 compression ratios and would run on almost anything that would ignite. It should be discontinued now as it is pretty much useless for most modern vehicles.

[@DxCBuG]

@@zacharyreynolds4303 higher octane fuel is not more expensive to make than low octane fuel. This is all synthetically done in a refinery. The price gauging for higher octane is literally marketing

[@electric7487]

@Engineering EхpIαined🌟 Scam alert!

[@egresk1]

Very interesting. My wife and I just did a 6500 mile road trip from the Midwest to the West Coast. I was wondering why so many stations had 85 octane fuel. We were driving her Turbo Chevy Trax and we always use at least 88 octane fuel. The Norms back home are 87, 89, 91. Out west it was 85, 88, 91. Thanks for the easy to understand explanation.

[@chrishansen2409]

Oregon and Washington are mostly 87 as a minimum, I don’t know about the east side of the states though

[@JoshuaPlays99]

In California its typically 87,89,91. You usually only find 85 in high altitude areas, especially places like utah.

[@csn6234]

Your problem isn't the fuel. It's your car. Speaking as a former Chevy Cruze owner.

[@lexithelexus7377]

Yep moving to diffrent states i saw it too

[@syzyphyz]

@@JoshuaPlays99 Yep i'm in Utah and 85 is all over the place, i use it for everything but my car (lawnmowers etc).

[@RickJohnson]

11:43 - Not too much different from the early 1980s and before when regular (leaded) gas at 88 octane was available, but you weren't supposed to use it in cars with catalytic converts that *required* unleaded fuel. When they phased lead out, ARCO and other stations sold an EC-Regular with a lead substitute to satisfy the requirements of these engines until the gas was phased out entirely. Just because it's sold doesn't mean you should use it, but today (and in the past), nozzle sizes differed enough to attempt to coerce drivers into using the right fuel by making the wrong nozzle impossible to use in the wrong tank.

[@Harry-zz2oh]

When I was young a century ago, we could go to a service station and buy white gas. Now you really have to look to find it. My neighbor uses it in the engines he repairs and operates but he has to go to the airport to buy it.

[@NathanKrick]

I recently drove from Arizona to Indiana and back. I passed through 2 states (or at least areas) that used 85 octane (New Mexico and the Texas panhandle). The car I was driving clearly says that a minimum 87 octane is required in the manual, and on the gas cap. I ended up using 87 in Texas (the midgrade at that station) and 88 in New Mexico since that was the midgrade in NM. Unfortunately, 85 octane doesn't seem to be cheaper than 87 anymore since the 85 that I didn't buy in NM and TX was similarly priced to the 87 everywhere else. If 85 is cheaper, than the gas companies are just pocketing the profits.

[@cliffordsquire2333]

The gas companies are lining their pockets which is a big part of the reason gas is so high that and no one want's to stand up to them since who's in office now.

[@jeremyswalley8625]

Well use mid grade

[@mikej238]

Prices vary because of state taxes not refinery. Liberal state = higher gas tax

[@anonymousperson2886]

Are you calling Texas liberal?

[@Nonamguys]

I live at over 7000 ft elevation, and have never had my engine knock with 85, but this is good to know and will use higher octane (when I can afford it) going forward!

[@katieandkevinsears7724]

I was with my brother in Colorado in 2001 in his 96 Ranger. It was only a 4 cylinder and lost so much power with the elevation, we couldn't do the speed limit. He kept trying the higher octane gas and it did nothing. I told him to try the 85 and we magically got the power back.

[@rogerdodrill4733]

That was magical, higher octane can only make more power if more timing advance without ping,if timing don't advance ,power won't either.

[@williamjones7821]

I heard somewhere years ago that much of what they put into gasoline to raise the octane is actually BUTANE, which I think burns LESS WELL than the gasoline it is added to. So higher octane perhaps did not burn as well or have as much power. I think this is why motorcycles don't use higher octane -- the gas caps allow fumes to leak out easily, particularly over the hot engine. So butane would leak out, and octane would fall quickly after the fill-up.

[@keilet]

​@williamjones7821 Incorrect. Butane is a gas at atmosphere. Ethanol is mixed with gasoline to increase octane.

[@e-curb]

@@williamjones7821 Gas tanks are at the opposite end of the car as the engine. Thus, it doesn't matter how hot the engine gets, the fuel temp in the tank won't change. Besides, all gas caps since 1972 have been sealed.

[@e-curb]

The reason your brother's truck made less hp with high octane is because its engine is low compression. When you put high octane fuel in a low CR engine, it will make less hp than low octane. There is only one function of high octane: to fuel high compression engines.

[@thewtfr]

I've lived in Colorado my whole life and have been using 85 for every car I've ever owned except my turbo subaru without any problems. Most people here seem to use 85 unless their car requires at least mid grade

[@trevorsmith4597]

Yeah. I think this video is aimed at people who live at sea level. I’ve never had issues either. Truck runs great

[@IronicallySarcastic]

What happened with the Subie? Did it have issues or you simply put higher octane fuel in it?

[@stevk5181]

My "old" truck ('02 😅) doesn't specifically state to not use 85 octane rating fuel. However my 2010 Focus does, and states lower than 87 octane could damage the engine. So the truck gets 85 "regular" and the car gets 87 "midgrade".

[@tybick12]

@@IronicallySarcastic forced induction engines generally require higher octane fuels than naturally aspirated engines do. Most recommend 91 or higher

[@onomatopoeia162003]

There are some that only take E-85.

[@michaelhess4825]

Over 25 years of driving a dozen vehicles at 5k or higher (I live in Wyoming) 85 octane has never been an issue. Knock sensors prevent damage. And the hundreds of thousands of vehicles at this altitude doing the same thing, is pretty good evidence it just doesn't matter. When I tow with my hemi, or fill my fiesta st, I do use 87. My BRZ gets 85 then 87 at alternating tank fills, never dropping past half.

[@javaman2883]

All the vehicles running on it is not evidence that 85 octane doesn't matter, it's evidence that the electronic systems are trying to deal with it. That results in decreases performance from your car, lower fuel mileage, and possibly shorter lifespan of certain parts.

[@theBear89451]

@@javaman2883 Like everything in life, it is about tradeoffs. Saving money is worth the reduction in power and engine life for most people.

[@alexurban8630]

My 2001 Wrangler's owners manual states 85 is the manufacturer recommended gas so I'll keep using it with no concern

[@cnorton1us]

I've lived in the Northeast US/New England since I was 3, where regular gas is 87 octane and premium is usually 92 or 93. I remember the first time I took a road trip to Colorado and saw that 85 fuel. Although it was cheaper, I stuck to the 87 considering there was a sticker right on the fuel door stating that was the minimum. Even though I was sure one or two tanks of that wouldn't destroy my engine, it just didn't seem worth it. Especially considering how much the power was down anyway due to the thin air.

[@michaelgriffin1601]

From Denver and been using 85 on all my regularly aspirated regular compression ratio vehicles since forever. Never an issue, but my vehicles dont see anything near sea level. If i was going to take one on a road trip East or something just make sure it has 87 in it and its good, but most road trips involve going up in elevation here anyways so literally not an issue and havent been throwing money away on preventing knock that isnt even close to occurring. His example of the boosted F-150 towing through high elevation and back down again is a good example of what not to do. Living in a city where your elevation from day to day only changes by a few hundred feet on regular commutes then run what is needed based off elevation.

[@thomaskendrick2221]

~7:00...."New engines can compensate for this (altitude), because they have EFI and they have electronic ignition timing, so you can maximize horse power and you can maximize efficiency and you can minimize knock by playing with your exact a/f ratio and by playing with your ignition timing" As someone who lives at and drag races at high elevation, I can assure anyone, that no matter the A/F ratio fiddling, no matter the Ignition timing tweaking by any ECM, ALL NA engines are still going to lose ~3% tq, hp and cylinder pressure....per 1000' elevation....and that is quite simply b/c the air density decreases with elevation. There isn't "as much air" in a cubic foot of air. Doesn't matter if it's EFI or not. In fact, I have run my car here (at 4200' elevation at our track) then calc'ed the improvement for lower elevation...then gone and run my car at that lower elevation....and it's run that calc'ed number. This is an EFI car, BTW. A non computer controlled car could lose more power (more than 3%), assuming that one doesn't re-jet for the elevation. I think the real crux of the issue here, and the reasoning behind Ford's warning is when we talk about modern turbo charged (alt compensating) engines, such as Ford's Eco Boost. Most if not all modern Turbo charged engines use an electronic boost controller which is managed from the Manifold ABSOLUTE Pressure sensor. Absolute pressure. This means that a modern turbo engine is going to manage intake absolute pressure at the same level, up until such elevation that the turbos no longer have the capacity to maintain that manifold pressure. Below that elevation (whatever it is for a given engine/turbo combination...it's 12,000' on our snow cats, at work) you'd have the same absolute intake pressure at any elevation....but at "high" elevation, you can only get lower octanes (85, 87, or 91). So, telling yourself that you could run, say, 85 at high elevation b/c "less cylinder pressure" in the case of a modern turbocharged engine....that would be folly b/c that engine/mgmt system is going to keep intake pressure (and thus, cylinder pressure) absolutely the same regardless of elevation. Compounding the problem with detonation, is that a turbo must work harder to maintain that same intake pressure at higher elevations; the pressure ratio is greater, the compressor needs to spin faster and exhaust pressure is likely higher too, to achieve that same manifold pressure, the higher up you go. All of that adds up to what? Higher intake charge temps...which does what? Increases the propensity for knock. But your octane options are lower. Hence....Ford's warning. Back to NA EFI engines, in practice, at high elevations, I've found NA, EFI engines to be quite able to run just fine using the "old engine" octane requirement curve that you've posted. I ran a truck I had for 300,000 miles on '85 octane. 9.5:1 compression, EFI, towing my boat through the rocky mtns, in up to 115*F ambient temps....elevations ranging from ~4000' to 7000' where I live. Truck didn't care, ran great and lasted way longer than long enough. I'd re-examine this topic and look at it through the lens of today's turbo charged engines with Electronic Boost Control, which have become quite popular compared to engine offerings during the "old engine" times.

[@ChurchAutoTest]

Thank you. This entire video could have been condensed to about 2 min saying "Don't use lower octane fuel at elevation in a modern turbocharged engine because they compensate for reduced atmospheric pressure by increasing manifold absolute pressure". There's nothing wrong with dropping 2 octane points at high elevation on non turbocharged engines.

[@jimb4090]

Exactly right. Racers, piston engine aircraft owners, and the terminally curious will have researched this topic and come to the same conclusion as you present. Short and sweet.

[@ChurchAutoTest]

@@jimb4090 Well you know the old saying, "engineering explained - just smart enough to be dangerous"

[@EngineeringExplained]

Yes, less elevation = less power, bc there's less air. Stated throughout the video, and in big text at 7:54. Optimizing for efficiency (which also increases power) happens when you have electronic ignition control, regardless of elevation. That doesn't mean you make sea level power, it means the control system compensates and adjusts timing accordingly. Old engines don't do this. As mentioned at the end of the video, turbo engines increase over atmospheric pressure, so you still need higher octane fuel.

[@ChurchAutoTest]

@@EngineeringExplained You missed the point. Engines are rarely octane limited at light loads. Most can reach MBT at 70-80 kpa of manifold pressure or less without knock. That's why they don't need higher octane at elevation, because they aren't generating enough cylinder pressure. You can advance the timing all you want, but past a certain point all you're doing is reducing efficiency and increasing bearing load. It is only when you have a turbocharged engine with absolute pressure targets (at an elevation where the turbos can still reach those targets) that you should be careful about reducing octane, as Mr. Kendrick adroitly pointed out.

[@kylegreen378]

I like your teaching style, and I'd rather have you teaching my engineering courses than 95% of the profs that I have had. Bravo my good sir

[@tommartin2360]

Agreed. If my physics and engendering profs used car engines in their examples I might have perked up a bit more in class. just sayin

[@nealbradleigh5069]

I concur. Can we get this guy cloned and into Public schools asap?

[@noahway13]

And I can't stand when my teacher spends so much time writing on blackboard or white board. This guy has it done already.

[@ericolens3]

@@nealbradleigh5069 How many clones? There's 50 states with each state having at least 3 major cities each. Or are we just closing him for the universities? In short, not if we should clone him, but how many do we make?

[@super8bitvideos]

its exactly how professors teach, the only difference is that he's directly in your ear and right in front of your face.

[@almuliman]

Perfect timing. I'm visiting and driving through Utah into Arizona and came across 85 octane gas yesterday. Definitely made me go "Whaaaa...?!?". Now I know. And no, I chose 87 😉

[@fzr2k840]

You chose well. I once put in 85 during a road trip and it messed the car up. Enjoy your trip!

[@TriNguyen-nl7qo]

@@fzr2k840 Did you have an octane booster with you when you put the wrong gas in your tank?

[@JimmyMon666]

I see it a lot in Utah. And I'm usually in the SouthWest corner since I come from Vegas, and the elevations in St. George aren't all that high to begin with. It's not that much higher than Vegas (about 600 feet higher). Most of the population of Utah lives down in the valleys, not up in the mountains anyways. Salt Lake is about twice my elevation though at 4200 feet. I admit I have used 85 octane before. I didn't know better until this video. It's not really going to hurt anything if you do it once and you aren't driving your vehicle hard. Plus it was mixed with the better gas from my city.

[@fzr2k840]

@@TriNguyen-nl7qo No, it was a rental

[@jwenting]

should have chosen 92 or 95. That's what gas should be. That's what it is pretty much worldwide except in the USA where it's supposedly "premium"...

[@hondaben7969]

Thanks for putting this together. I've been selling Honda vehicles for 17 years. I live and work at about 700ft of elevation in the Driftless region. It's nice to have this video to share with my customers who are asking about their mountain trips with their families in their new rides.

[@kevinstarski1598]

What's Driftless region?

[@LionRunner]

Sadly here are the comments when I share this video in a FB group here in Colorado- User 1 - Toyota told me 85 is fine here and I'm in a 2017 - same everything as your 21. I never noticed a difference anywhere other than my bank account so I run 85 🤷 User 2 - I live in the Springs and been using 85 in all my vehicles for 25 years without any issues. I occasionally use a fuel cleaner, but that's all. No know issues with my new or used vehicles. My elevation is 6000 ft. User 3 - 85 for life! I’ve never noticed a difference when I run 85 or 91. User 4 - I'm in a 98 4runner, so maybe the age is the reason but I've compared 85, 87, and 91 up at ~6k-8k feet where I drive and haven't found any difference. User 5 - 85 is all I pump at 8,000 ft elevation in Colorado. Pumped 85 in my 4.7 sequoia my 4.0 4Runner and the 5.7 in the lc User 6 - I run 85 in high elevations. Anything higher in a low compression engine is just throwing money out the window for a placebo effect. Many more comments like this..

[@EVLS10]

That's because it is fine. He lightly touched on it but the crux of the video should have been that they are lying to you. Basically all modern vehicles have knock sensors. Meaning if you start knocking for any reason then the ecu will pull timing and that's it. So you are fine to run 85. Just in some vehicles you will lose power. The notice in the manuals is a cover their ass sort of thing. They don't want to be blamed if that stars align and either the ecu fails to save itself (which should be their problem) or if somehow you put low enough octane in to cause damage with knocking before the ecu can stop it or low enough that the ecu can't pull enough timing to stop it. 85 IS FINE IN MODERN VEHICLES. Seriously. They are smart enough to run on it. You really think they are going to build a car that could blow up if someone forgets and fills up with 85? No that would be silly. Because people willfully and accidentally do it all the time.

[@thelastgood1forever]

This needs to be the top comment.

[@DrWhom]

@@EVLS10 you should see what the Russians put in their cars - I don't know exactly what it is, but it smells like vegetable oil

[@MrPizzaman09]

I chose 85 in my Jeep Comanche while driving through Colorado since it was the only grade at the pump. I regretted it when I was in Kansas doing 80 mph heading into a 25 mph breeze...the knock sensor pulled back timing so far back that I was at WOT trying to keep up with traffic. Added some 93 and it was much better

[@paulwblair]

Interesting. I did a cross country this summer and noticed the low octane in Colorado. The station had higher octanes available and I didn't know how my car would run on 85 when I got to lower altitudes, so I got the higher grade.

[@ghost2coast296]

I always stop at Idaho Spring for gas on my way through the Rockies and wtf half the stations didn't have ANY gas, and the others had only 85. Next time I'll be bring a couple gas cans in the trunk.

[@ChrisLesmerises]

try running 25% E85 on top of 75% low grade. You'll save money and not have that knock.

[@be5952]

@MrPizzaman09 --- _"...so far back that I was at WOT...."_ You were at "Web of Trust"? "Wheel of Time?" "Wall of Text?" "Weak Operator Topology?" "War Office Transport?" "Wheels of Transformation?" Those are just the first six initialisms that came up in a Guggle search. Whatever the heck "WOT" means to you, many people (including at least two other 'car guys' I asked), have no clue what you're saying. *Please* just spell out a few more words and make the internet decipherable for everyone. Thanks.

[@MrPizzaman09]

@@be5952 Wide Open Throttle

[@OldBanHammer]

The rub that really stings is, here in Utah with the 85 octane regular fuel; we have some of the highest prices in the country. The oil industry is ripping people off.

[@moto5513]

No way you have some of the highest prices in the country, in California the price is almost $3.00 a gallon more.

[@derek133]

I just did a road trip from Washington through Utah and California. Utah was the cheapest by far. You lucky people!

[@selfdo]

CA is still higher than "Yew Tah". It's all a matter of supply v. demand, though. Utah's economy is relatively prosperous, so the price the retailers get will tend to be higher. CA's is still higher NOT because of any "better" economy (in fact, it's in the toilet), but due to insanely HIGH TAXES.

[@Schetmesa]

Yea and you have two refineries there

[@senorpepper3405]

But atleast you can have more than 1 wyfe😂

[@d.jensen5153]

My Honda CRV 'Earth Dreams' engine has never seen anything but 85 Octane. After 100,000 miles it still runs like a dream. But it's never been anywhere near sea level.

[@calebmenker988]

Yea I've got an MDX that's run on 85 for 21 years and it still runs absolutely beautifully

[@cartere9981]

@AlWorth9738bro stfu they are pretty high compression engines, bet they make more hp/liter then your American car, assuming you have a American car cause of your comment. Ignorance is common with American car owners

[@mikebradford7780]

Actually its just a car.​@AlWorth9738

[@VoidSinister]

​@AlWorth9738 what car do you have, big boy?

[@wta1518]

@AlWorth9738 All cars are toys. Try an airplane.

[@SteventheGrey]

In addition to the turbo engine and being used to tow, F150 is also available with a 36 gallon fuel tank, increasing the odds that you'll end up at a lower elevation with 85 octane gas.

[@doctorscoot]

Have you ever seen one of "Greg's planes and automobiles" videos where he talks about Octane Ratings and manifold boost pressures in WW2 era fighter engines? He goes into tons of technical detail about two stage turbo-supercharging and power outputs at different altitudes...

[@stevedugas8988]

Greg's videos are among the most interesting technical posts on the 'net.

[@doctorscoot]

@@stevedugas8988 yeah i love 'em

[@RhodokTribesman]

One of the best historical research/engineering channels on youtube by far

[@SugarBushBoys]

Greg explained that US fighters evolved to outperform German fighters due to the availability of higher octane fuel. Manifold pressure was allowed to go higher producing more horsepower.

[@SSChambers1]

I still occasionally get significant knock with Shell/BP 93 octane here in Ohio from various stations, pulling timing as much as 12°. The same brand/octane fuel on a trip down south resulted in 0 knock. I swear, Ohio has diluted horse piss as fuel.

[@d-rockpain4250]

I've been anti ethanol this whole time. We maintained a truck fleet and ran ethanol in 1/2 for several years, and the increase in maintenance cost way outweighed any potential benefits. There was a 15% higher overall cost to maintain the ethanol fleet, and the mechanical issues were bigger lower end damages. They stopped the ethanol testing immediately. Any similar stories? Tell em.

[@ValConB]

D-Rock Pain - What was the ethanol percentage that you used in that truck fleet? I think in my area it is 10%, just wondering if it is different in other parts of the country.

[@d-rockpain4250]

@@ValConB same. Up to 10% unless E85 I believe was allowed 15%. (Was 20yrs ago roughly). The fuels were run through trucks And fans, since most hydrostatics and big trucks were all diesel.

[@smileyguyz]

@@d-rockpain4250 Unfortunately ethanol is here to stay. It sucks but it's much much better than the alternative, which is leaded fuel.

[@d-rockpain4250]

@@smileyguyz What were they using from 1996- 2005/6? There is a 9-10yr overlap of lead being removed, and ethanol not yet being added.

[@AlejandroLopez-ze8gu]

@@d-rockpain4250 Different additives like MTBE and BTEX Complex

[@SuperDerfmaster]

I always wondered about the 85 octane gasoline, when I was in the mountains. My owners manual recommended minimum 87, so I stuck with it. Now I'm glad I did.

[@sartainja]

Back in the 1970’s Honda use to put a “high elevation” knob on the carburetors of the motorcycles that you pull if you were over 5000 or 10,000 sea level to help the engine run better.

[@williamgolden839]

Around 1980 Toyota pick up trucks had a high elevation system. Colorado trucks if I remember correctly

[@nobodytoyou4887]

Glad to have learned this, here in CO they sell 85 octane, thought it was just normal because of the higher elevation , good thing my GMC is naturally aspirated and doesn't leave that elevation much.

[@shauncore808]

Same here with my NA V6 Colorado living out in Salida. I just looked in the manual and it says using under 87 can actually hurt the gas mileage. I've been averaging around 20 mpg since I got out here and just kind of figured that's what it is. Now I'm wondering if that's just because I've been using 85...

[@dan.r9220]

I moved out here from MN and never even thought about it when I just grabbed the lowest one from the pump. I looked after watching this and my local station has 87 but jts 0.20 more than 85. I can't believe it's that much cheaper than 87.

[@Fattts]

Just drop an octane booster in for safety when you come down towards sea level and you'll be good

[@imoffendedthatyouareoffended]

I also live in colorado, I have a turbo’d car. It’s really not much of an issue. My car typically knocks if I’m running my ac or my heater. I’m tuned and still it’s been solid.

[@dan.r9220]

@@imoffendedthatyouareoffended your running 85 in a turbo car?!?!?!?? Who would tune your car for 85??

[@mgweir3252]

I have never had an issue with 85 octane fuel. I live at 6700 ft above sea level. The only vehicle I have that needs higher octane fuel is my Harley. My 20 year old Silverado an 7 year old Nissan both run fine on 85 octane and have never knocked or had pre detonation.

[@oldman-zr2ru]

I live at 6000 ft. and have used 85 octane for decades. I still have my 92 F 150 with 240,000 on it and it does just fine. My 99 Yukon and 99 Cherokee, same thing.

[@paulo123-]

Do you drive like an old man on Sundays? My guess is yes

[@oldman-zr2ru]

@@paulo123- You can't drive fast here anymore thanks to all of the Commiefornians that have moved here.

[@sungear]

Surprising how many dummies can watch this explanation and still think that every car needs high octane fuel.

[@willk4031]

* Higher manifold vacuum at full throttle on old cars, not pressure (hence the vacuum advance on a mechanical distributor)

[@charliemason4355]

I had a 1961 Rambler American Classic, inline 6 with 127 hp. The windshield wipers were driven off the intake manifold vacuum. Real fun when you're entering the highway at night in the rain and floor it. The wipers nearly stop.

[@johnl3487]

The real term is maniford pressure. The pressure is measured from a total vacuum. This is the only way to get the same number regaardless of the elavation of the car. At full throttle the "vacuum" would be less or nonexistant.

[@davewinter2688]

You are correct! I noticed that error too. That's a good reason for a vacuum gauge on an older carbureted vehicle. See my comment on the subject including my reference to the knock sensor which is essentially a microphone. Some might call it a transducer.

[@timdryden3778]

@@davewinter2688 some might call it a crystal that when vibrated, produces a voltage, to the ecu which alters spark timing, to compensate.

[@coleroyce]

Good info, I live in Wyoming at 7,200’ elevation and about 14 years ago when I moved here I was concerned and confused about all reg gas here being 85, then 89, no 87. I have a 2011 f150 eco boost and have been putting the 85 in for 10 years. You have me second guessing changing to the 89 in the future. Thanks for sharing.

[@dylanc2806]

if youve been putting 85 in it for 10 years and havent had any issue i wouldnt bother

[@coleroyce]

@@dylanc2806 I agree. I still use 85 for that reason. I do upgrade if I’m on a trip at lower elevation though.

[@pipertripp]

I’ve been in Denver for 20 years and have used 85 the entire time. Have never had nor heard of anyone having issues. I’m also not asking around but seems like I would have heard something by now.

[@adamcornell6738]

I'm surprised there wasn't mention of the purpose of the knock sensor in modern engines. EFI engines will adjust ignition timing to eliminate knocking when the sensor detects it. Carbureted engines would be more likely to knock than EFI. They lack the ability to detect knock and adjust ignition timing. You would literally have to change the jetting if you changed altitudes substantially.

[@FrancescoBarberaMusic]

While you would be correct there are still limitations on that those knock centers are going off the assumption that you're going to be using a minimum of 87 octane fuel Purposely going below that limitation will throw the timing and knock outside of what the knock center can compensate for

[@adamcornell6738]

@@FrancescoBarberaMusic right. Like running 87 in an engine that needs 93 or such. I was just a little thrown off by this video.

[@Ethan-um7cp]

EFI engines will not "eliminate" knock. WTF? Blow up peoples cars much? SOME modern vehicles with EFI have knock sensors AND an ecu with the ability to retard timing to "REDUCE" knock. Sometimes this can eliminate knock and SOMETIMES it does not. Not all knock is audible in the cabin to the driver, but all knock causes engine damage over time, even though you can't hear it or feel it.

[@adamcornell6738]

@@Ethan-um7cp you didn't read what I said correctly.

[@Ethan-um7cp]

@@adamcornell6738 Here is your quote dipshit "EFI engines will adjust ignition timing to eliminate knocking when the sensor detects it." Guess what , that is wrong.

[@jasonkalihi5603]

It's kinda like when I first started driving back in the 90's, and leaded fuel was still readily available, even though really no cars produced since the 70's were able to run leaded fuel.

[@lrich8181]

1975 was when unleaded was required in cars in the US.

[@LA_Commander]

My mom bought a 1979 Honda specifically because it was the last year that model could run on leaded gas. Starting in 1980 it was unleaded.

[@DrWhom]

@@LA_Commander your mum wanted to put lead in the air?

[@LA_Commander]

@@DrWhom yeah and she ate babies and pulled the wings off bees too, are you happy now?

[@carrtb]

@@LA_Commander I love this. I did EXACTLY the same thing but with a different make. The 1980 vehicles were out toward the end of ‘79 but I opted for one of the two remaining ‘79s. They didn’t have a catalytic converter (or any other emissions control device) either. It was a sad day a few years later as the powers that be took away the leaded gas pumps, Union 76 was the last bastion with their Leaded Supreme.

[@303nitzubishi4]

Fun fact that disclaimer has been in Ford owners manuals for many years, long before Ecoboost was even a dream. Wish this subject was covered in such detail about 15 years ago so I could have shown my boss. Our fleet was mostly late 90s- early 00 Rangers with 2.3 & 2.5l SOHC Pinto engines. Some had the dual spark heads. They pinged on anything less than premium, even here in Denver. I'm sure it was party due to older engines with carbon buildup but still. I tried to explain why to my boss he got kinda pissed. I kept trying to convince him to run premium in his company truck for a few weeks to prove my point, but he never did. "These POS 4 cylinder trucks are not worth spending the money for premium fuel" was his logic. We retired our vehicles just over 100k so that had something to do with his perspective too

[@hogibunz834]

I was literally thinking about this exact concept the other day. Totally needed this video. So good and so informative.

[@Bizzmark11]

Some cheap stations in Maine used to sell 85-86 AKI gas at elevations of only a few hundred feet. I mean within the last 15 years. Never thought about it, never had an engine start knocking (until I had conrod bearing failures..), but I pay more attention now. Good video!

[@randallthomas5207]

Conrod bearing failures can be caused by the increased load from knocking at levels too low too hear.

[@Bizzmark11]

@@randallthomas5207 Possibly, but my two experiences with this were due to a warped head letting coolant into the oil and an overheating BMW oilhead; both went after a scorching hot day of stop & go city traffic.

[@markm0000]

@@Bizzmark11 BMW, well there’s your problem circled for you.

[@randyw3553]

The octane rating of each grade is usually 2 units lower at the higher elevations. I've never had a problem with either older or newer cars. When returning home, I simply replenish the gas as soon as I start seeing stations with higher octane ratings.

[@crashtech66]

This is the truth. Also if you know you are traveling to lower elevations and have reason for concern, simply fill with higher octane before leaving.

[@rod3134]

One other thing I believe needs to be emphasized is compression ratio on octane... Even at sea level many modern cars have different compression ratios. The piston compression ratio will affect the knock if the ratio is low or high and the wrong octane fuel is used. Thats why dragsters and race cars tend to use high octane gas. It helps to lessen cylinder ignition before the piston reaches the proper ignition point. My rule of thumb at sea level is to only use higher octane fuel for any gas vehicle at or above a 10 to 1 compression ratio. So far this hasn't failed me. Most of my vehicles were driven well over 100k miles with no issues.

[@TestECull]

Modern EFI systems can play with the tune of things enough to run just fine on 87 up to 11.5:1 or so.

[@rod3134]

@@TestECull Yes this is true to a point. I tested it myself on my Nissan 350.and 370.z. there was a noticeable change in performance. And I did it with mid grade gasoline. I believe for maximum performance across the board, high compression ratios should stick to high octane. Just my opinion after doing it myself. Lastly my sister had a modern SUV that stated it could use low octane gas. She had never ending engine issues until she started using 90 plus octane. I discovered her compression ratio was the same as my C7 corvette. My vette explicitly states high octane use only except for emergencies.

[@TestECull]

@@rod3134 Heh. All the more reason for me to stick to a C4 or C3 if I ever get a corvette then. Can feed those things half-stale two stroke that you found in your grandpa's barn ten years after he last mixed up a batch and they won't care. All of the engines you're talking about, though, will still run fine on 87. They won't be damaged by it. The ECU backs off the tune enough to see to this. They won't perform their best, but then again if you're driving on public streets you don't have any business calling for more than about 50-75hp anyway. Especially in something as aerodynamically slick as a C7 Corvette. IT's the older carburetted engines that you need to watch out for, because they *can't* de-tune themselves on the fly. If they're built with a 10-11:1 compression ratio you *have* to use higher octane fuel in them.

[@rod3134]

@@TestECull Agreed 👍🏽 I guess I'm a little selfish when it comes to power. I always want a 100% at all times. 😁 Never know when you need to get out of grandmas way.😆 Oh yeah... look up the compression ratio of modern cars. Most run way above 10 to 1. The chevy 6.2 liters generally run 11.5 to 1. I'm pretty sure that's why my stock Horsepower is close to 500hp. Being a computer guy by trade I don't fully trust the ECU electronics enough especially knowing how detonation can destroy an engine.

[@eliwhite5548]

Anecdotal evidence like the kind you used isn't very helpful. My rule of thumb has been to use the cheapest gas available and ignore compression ratios and I've had no issues either. My vehicles have all gone over 150k miles.

[@Jutsch80HD]

The lowest octane rating fuel you can even buy in Europe is 95 RON, which is equal to 90 AKI. Lower octane fuel (90 RON, equal to 87 AKI) was discontinued over 10 years ago in Austria and Germany, and those basically were the last countries to do so

[@Jutsch80HD]

@@bartekino RON and ROZ is the same, it’s just the octane number and that doesn’t say anything how much ethanol is in the fuel (E10 has 10% ethanol)

[@Jutsch80HD]

@@bartekino I'm not entirely sure. I think it's rather a minimum number. So E10 has at least 10% ethanol.

[@Jutsch80HD]

@@bartekino Apparently. I'm not an expert so I can't really judge that. I'd love to see a video about it tho

[@waycoolscootaloo]

@@Jutsch80HD US refineries actually meet higher tier standards than European refineries do. The US adopted 10% ethanol years before Europe did as a result. Back In the 90's to be precise. US 87 = Europe 91 octane. US 89 = Europe 95 octane. US 91 = Europe 97 octane. US 93 = Europe 99 octane. US 87 / Europe 91 is sold throughout most of the world today, except for Europe since most cars around the world run on it perfectly fine. So in Europe, you get ripped off since it's not an option like it is in most countries since it's cheaper than 95 octane in Europe. Canada and the US use the same octane rating system actually as well from the same refineries. And premium 93 octane in my city right now is $3.74 per gallon here. (€0.87 per liter) And then 87 octane is $3.10 a gallon. (0.82 per liter) 🙂

[@johnfrancis0063]

1976 Cadillac DeVille. 501cid engine with the QuadraJet carb. Lived on the east coast flatlands but occasionally went up to the Appalachian Highlands so I had to change the jets in the carb around 4000ft ASL. I became an expert rebuilder on those carbs.

[@GlenTheGuesser]

EE = Engineering Explained and EE = Educational and Excellent!

[@calholli]

EE = Elongated Eggplant

[@GlenTheGuesser]

@Brian Rosa That worked! First win today. Let's Go Giants!!!

[@lhurst9550]

Yeah the solution is just don't go down to lower elevations, 'tis spooky there, very weird people.....

[@sushislicer3742]

tell me about it

[@walkerforsyth6221]

Truth.

[@brokedonkeygarage6017]

Hahaha

[@majist0]

The beach and humidity are totally over-rated.

[@squatchhammer7215]

I know, Wyoming is weird.

[@lilsammywasapunkrock]

I'd really like to see a video on ethonal blended fuels. I drive an "older" fuel injected car, and I live at a higher elevation. It's a 86 v-8. When we converted over to ethonal fuels, I lost power and economy. But we also gained equivalent "octane" rating by using the ethonal. To get some of the power and gas mileage back, I actually bump my base timing up quite a bit. Base timing is 10° and I can usually get up to 16 or 17° without any knocking or issues. Even though it's old, it still has computer controlled timing, but it's also really low compression at about 8.5:1. Now on a newer car with variable valve timing, I still don't see an issue, as the electronics should be smart enough to detect any sort of knock and pull back timing. On a turbo charger car, the argument against lower octane fuels makes perfect sense, because they artificially raise combustion pressures and essentially negate the losses from elevation. Personally, the best mileage I get is on non-ethonal low grade fuel. I usually get the same, or even worse on premium. I used to drive 100 miles round trip 5 days a week, and this was around the same time that we started switching over to ethonal in my state. I routinely got a 7% dip in gas mileage whenever filling up with "e10", so I would avoid those until they were all gone. Since my drive was 50 miles almost exactly each way, I had a 22 gallon gas tank and often averaged around 30 mpg if I was careful. I would routinely get right around 600 miles to a tank. I did all sorts of things with my driving habits to try to maintain or beat that 600 mile range. My personal record ended up being 652 miles averaging about 35 mpg on a full tank. But that was being really careful and trying to do 55mph on the highway. Messing with it, I could easily maintain 70mph all day long using cruise control and still get 30mpg. I decided after doing the math that I would rather save the 20 minutes a day then save the $3 dollars a week and kinda gave up on maximizing millage. Oh, and incase you were wondering, it's usually not worth it to run non-ethonal fuel. It's usually between 10 to 25% more expensive, and at most you will only gain 7% difference, so cost wise it's pointless.

[@alflyover4413]

That depends very much on the vehicle. OBDI autos gave me 30% less mileage on E10, compared to ethanol-free, as well as soot in the tailpipe, so they were burning more fuel. For a OBDII car you are right, but I am using E0 in my older OBDII because it isn't rated for E15 (now the gasohol standard by government mandate).

[@drunvert]

Ethanol has less energy v gasoline. So it fixes knock but you need more of it.

[@Knirin]

My brother’s 2013 Chevy Silverado gets about 10% better fuel economy using E15 than E0. No idea why.

[@surrelljr]

Thank you! You finally got me a detailed explanation, I use 87 octane fuel here in my vehicles in 5000+ ft here Wyoming since I started reading that it was recommended for my newer vehicles. It makes sense now, I grew up in the 1970’s with carberation systems and we went with the best combination that gave us maximum performance. Onboard computers on my 1993 and newer vehicles do a lot, with a detailed description I feel better about what I am doing.

[@NaziHampster]

So the upshot of this is, the car manufactures are covering their backs just in case some smart arse tries to sue them for engine damage due to `incorrect` fuel rating usage at the non specified altitude. Very interesting. Fuel for thought. Thanks.

[@silverfox__12]

And I wonder how well that law suite works when people use diesel in place of gas?

[@NaziHampster]

@@silverfox__12 Well to be honest, that's just human stupidity.

[@martyscholes119]

People just know to use regular gas. I grew up in the Rockies and was told that 87 octane fuel at sea level tests at 85 octane here, so they are the same fuel, which I am now learning is incorrect. I would be stunned if manufacturers do not plan for this scenario during testing. High altitude with lower octane is not a new trend.

[@alxace]

@@martyscholes119 Clearly manufacturers account for this scenario. That's why there is a warning in the owner's manual and that's why Jason made this video to explain it.

[@Kandralla]

@@NaziHampster I don't know that I'd call accidentally using an incompatible fuel that comes from the same pump with the same looking handle stupidity. It's basically the same human factors fail as selling 85 octane as "regular" and not something distinct.

[@ajfurrell3744]

Literally this situation with VW in NZ where I used to live. We have 91, 95, 98 octane fuels. VW recommend 98 octane in the 1.4 petrol turbo engines as per most euro cars too. People who put 91 octane in were cracking pistons and the first thing VW was testing was the fuel in the tank. They were declining warranty claims for any that tested with less than 95 octane.

[@nfdr0kk3rz]

Its pretty mad how their 'premium' fuel is what our regular everyday fuel is

[@ajfurrell3744]

@@nfdr0kk3rz America uses a different scale to rate their fuels on, but I think they're about the same as the rest of the world when using the same rating system.

[@mark8200]

@@ajfurrell3744 Of course they do

[@waycoolscootaloo]

@@ajfurrell3744 Eeyup! You are correct! The US system for determining octane is actually a better method as it accounts for the MON test which Europe completely ignores. The US octane rating better represents the real world burn of gasoline under atmospheric conditions. US premium 93 here in the US is the same as 99 octane in the UK. Canada also uses the same octane rating system as the US. And US refineries actually meet higher tier standards than European refineries. 🙂 Fun! Fun! 😎

[@rockymntnliberty]

Since I have used 85 octane on all of my gasoline powered vehicles for most of my life, this is somewhat interesting to look back with this information. Estimating my number of miles, my miles per gallon, and the additional cost to go from 85 to 87 octane, I would have spent an additional $4,000 to $5,000 on fuel over the last 42 years. Would this have made a significant difference on longevity of vehicles I doubt it. I currently have two vehicles that have 130,000+ miles, I've had a couple with over 200,000 mIles, and one with over 300,000 miles. I think I'll keep taking the savings at the pump!

[@potatoheadhaoy]

I'm surprised you're not angry that these guys are literally making you choose between garbage fuel and losing money.

[@EricBurns1]

Certain cars require certain octane. If you use an octane lower than what’s necessary it can cause engine issues and you’ll have more trips to your mechanic. Example: every Subaru requires premium. You try using lowest one at the pump and it’ll mess up your engine

[@EricBurns1]

Also, gas today with ethanol is not good on old cars (say muscle cars) because their engines weren’t made to have any of that in the tank

[@davidfleck2596]

@@EricBurns1 not true, only brz, wrx/sti require 93 aki fuel. Everything else only requires 87.

[@pasta-eo5mt]

@@EricBurns1 That's not true. Most Subaru models use 87. This is straight from Subaru: "If you drive a Crosstrek, Forester, Outback, Legacy or Ascent, your vehicle is designed to run on 87 octane, or regular fuel."

[@jamesglass5402]

When I was younger engines that I had or built myself had 10.5 to 12.0 would seldom run on the regular gas would knock terribly so they would only run on what was called premium or Ethyl gas. I understand why you need to explain this to people that don’t have that experience. This was a very good explanation. Both of the current cars that claim that they will ok with E-85 but I have never used it.

[@markjwems1]

This is a fantastic video with a great lesson. I have explained this concept to others several times in the past, although not quite as deftly. However, I always include an explanation of octane vs. heptane (ie. the influence that the number of carbons on the molecule chain has on ignition temperature/ignition pressures). A basic description of petroleum refining processes can be helpful. I wonder if you would be interested in creating content that addresses that part of the subject.

[@uliwehner]

there is your problem, people's eyes glaze over when you get into octane, heptane, cetane, propane, butane, etc. they hear charlie brown noises......

[@hawkertyphoon4537]

Good idea! Send EE to a refinery and cover the important bits for us Petrolheads.

[@Bloodcurling]

One super-specific counterpoint. The Skyactiv-X engines run best at 85 or 80 octane. So, if those ever start to get sold and become popular, it would be optimal for those engines

[@pipercdefgabc2005]

If people would learn more about their cars, trains, plans and factory's and take responsibility this world would be great. God put you here and I have to live with you!

[@mcinteer19]

I came to figure out why when I travel to the west and fill up with 85 octane my vehicles get better fuel economy. In the past month I’ve driven to Colorado and the Black Hills with both of my vehicles and both got significantly better economy after filling up with lower octane.

[@michaelblacktree]

I remember seeing 85 octane at many gas stations, during road trips out west. I always wondered about that. Thanks for the info! 👍

[@electric7487]

@Engineering EхpIαined🌟 Scam alert!

[@javaman2883]

AS pre 1990 cars get less common, the 85 octane gas should be disappearing for good.

[@forumtyish]

It's interesting because for I think 2020 or maybe 2019, whatever the most recent year's data has been reported, the US DOT says the average age of a vehicle in the US is something like high 11.x years, nearly 12. It was less in past years, very slowly increasing over time, but still it would suggest that we have long since passed the time when any reasonable person should expect a pre 1990 car to be even remotely "common" and thus there being a justification for such fuel - And keep in mind this video uses 1987, per the referenced study, as a modern engine that didn't really benefit from such fuel. So I don't think it should have been allowed for even the last decade or two.

[@lexithelexus7377]

Yep moving to diffrent states i saw it too

[@rogerdodrill4733]

@@javaman2883 not from high locals

[@boost331]

Cant say I have ever seen this type of fuel. I do however regularly use E15 which has an 88 octane rating. It is cheaper per gallon than 87 and has more ethanol to burn cleaner. There is a very slight loss of MPG as expected with the higher ethanol content, but I only notice that durning city driving. With majority highway use my MPG stays the same as when using 87.

[@msmeyersmd8]

Excellent video. This has always bothered me tremendously. Especially driving a High-compression LS engine at 3600 feet and only 87 octane fuel is sold as premium. Manual says 91 octane. Same with my supercharged small block Chevrolet. The engines, even the high compression Normally Aspirated LS does not "know" we are at 3600 feet. Electronics "knows" and compensates somewhat but I'm getting screwed because the performance will drop via timing changes and lower relative compression. The supercharged engine makes selling of 89 octane as premium fuel an engineering travesty. The scary thing is they push the octane for 87 Premium by bumping up the ethanol level as high as possible. Many tests over the years have shown way over 10% ethanol. Now, I'm forced to avoid knock by manually retarding the timing and dumping more fuel into the engine to cool the A/F charge. That costs money. I've had one low milage engine ruined by this practice. It's pissed me off for over 30 years. 3600 feet and I pay premium prices for s**t gasoline. 91 down 87 octane is a significant hit. It's not like we are cresting the Rockies or the High Sierras here.Thanks for addressing the issue.

[@johnferreira93]

Where the hell is 87 sold as premium? I’ve gotten gas over 10k feet (Leadville) in Colorado that still sold 91 octane.

[@Discretesignals]

If this is a factory stock modern vehicle that hasn't been altered, it does know you are at 3600 feet. It is measuring the barometric pressure. How do you think altimeters work?

[@lexithelexus7377]

Yep moving to diffrent states i saw it too

[@brnmcc01]

@@Discretesignals yup it's called manifold 'absolute' pressure sensor, or MAP sensor.

[@eaglescout1984]

I mean, there really is just a handful of instances where the sale of a product being outlawed in the US (and/or individual states) and most of those were for health and safety reasons. In fact, you can go to any big box home improvement store, and they have multiple items for sale that violate building codes. And it's because we tend to adopt the practice of "caveat emptor" in this country.

[@beltaxxe]

The fact that the laws are based around old carb engines is just a testiment to how out dated current laws are.

[@reelreeler8778]

and is a testament to how effective lobbyists are

[@Kandralla]

I have more "old carb" engines around my house than I have new and I'm not even trying.

[@lamoona4269]

@@Kandralla yea but most people don't.

[@nelsblair2667]

Moving at the speed of Congress. Even the glaciers move significantly faster; which may be why so many glaciers are gone.

[@spacetoast7783]

@@reelreeler8778 you mean ineffective

[@eriks2962]

Man! That was great. I am a computer scientist with no interest in working on cars. But your presentations are so good and so clear, that I really want to see them!

[@alphatripduce]

I was on a road trip in the forester I had in college and the group I was with was covering my Gas ( because I had everyone's luggage) and they insisted that they wouldn't pay for anything more than regular on the way back the knock had caused a spark plug to work it's way out

[@tomdillan]

When I lived in northern Utah they sold 85 and misses asked me why I didn’t use it because it was cheaper. I had read my car manual and it stated no lower than 87 octane. All the gas stations were 85, 89 then 91 octane fuel.

[@JustBen81]

I still found this very informative even though the lowest octane level gas sold where I live is 95 octane. They stopped selling 91 octane gas over 10 years ago.

[@waycoolscootaloo]

Yeah, just to drive profits. Most countries have 91 octane still. Most cars are designed for 91 globally. (91 Ron = US 87 octane)

[@larsjrgensen5975]

I lost around 50hp with my 200hp Saab when fueling it with Europe octane 92 (guessing 85 US octane), because the engine tried to protect itself at highway speeds. Also found out that the car knocked more and then used more fuel to cool, so it was actually more expensive to drive with low octane then regular, because the engine would just use more of the cheaper fuel then the regular fuel.

[@TheSimon253]

I have never seen lower than 95 in Sweden? Do you have 92 in Denmark?

[@CaptHollister]

92 RON is actually equivalent to 87-88 AKI. When I had a 9-3 (two of them, actually) here in Canada it drove normally the very few times I put 87 in it, but it used more fuel. The difference was enough that it was cheaper to use 91 (95 Ron) or 94 (98 Ron).

[@larsjrgensen5975]

@@TheSimon253 I think 92 disappeared a year or two ago. My low octane drive happened 6 years ago I think and I used half of the tank and filled it up with V-power 99, to fix it. Some small stations only had one fuel tank, so they delivered 95 in both the 92 and 95 pistol, the only difference is the price they bill you. Where it gets tricky is when you hit that very rare station, that actually had a 92 tank, instead of giving the customer cheap 95. We now have 95 10% ethanol and 95 5% ethanol and sometimes a high octane 98, 99 or 100. Sadly we never got E85 here for my Saab, it is possible to buy a drum of racefuel, but the price is much to high to be daily driving.

[@strangeclouds7]

50 hp seems pretty dramatic

[@larsjrgensen5975]

@@strangeclouds7 Yep it is a big jump. My previous car: 2000 Saab 2.0 turbo tries to compensate for the bad fuel in multiple steps, then lastly it gives up and pulls the turbo boost down to the same level as the low pressure model. When knock is detected it adjusts the ignition timing and fuel amount in 5 steps, if the knock is still present it cuts the boost pressure in half. All this happens in seconds, so when the engine runs on low boost because of knock, if you let of the gas for 10 seconds the car will then run full power for 2 sec before the boost is lowered again. High octane fuel is also detected by the engine system and the engine will adjust to a little more boost compared to regular fuel (guessing around 5hp)

[@sixtyfiveford]

Some heavy misinformation/fear mongering here. Octane is the fuels resistance to burning/self ignition. The F150 here will have more power at high elevation with 85octane vs a 87/89/91 ect. Low octane ignites quicker and more completely in the combustion time frame. High octane burns slower. Now if you have a high compression ratio car that requires 91octane you will quickly find out you can't buy anything above 89octane at high elevation. Why??? because it's not needed. I love how marketing has convinced everyone that high octane= more power.

[@MrAruss99]

that statement is only true if there is no timing increase from 85 octane to 87. The cooler burn is marginal compared to an extra degree or two of timing, especially on an engine with conservative timing to start with like the f150

[@buckrodgers1162]

True, it is heavy on the misinformation. But what do you expect? It's all done in an effort to make more money by convincing people to buy the higher priced product. Gotta love how the oil industry is easily allowed to get away with this false kind of marketing (note the sarcasm). I mean I'm 3rd generation high altitude resident, my parents lived here, and my grandparents lived here. All 3 generations have used 85 Octane fuel regularly, and not one of the many vehicles we have had, both older and newer, have ever had a single issue with this. If anything this vid should be flagged as being 'factually false'.

[@walt1955]

I had a rental car in Quito, Ecuador in 2008 (Quito elevation in meters: 2,850m. • Quito elevation in feet: 9,350ft). All the gas was 80 octane which I had never seen before. I did not hear any knocking coming from the engine, but I was glad it was a rental.

[@TheCldmstrsn]

Thank you for this! I live in Salt Lake City and now use Plus (88 octane) instead of the 85 which the dealership said was fine but it really isn't! when I first got my 2022 Outback XT I had 85 and noticed some weird stuff but since I went to the 88 it performs perfectly.

[@wr3921]

Interesting video! Living in Wyoming, the "Regular" grade fuel offering was 85 octane pretty much everywhere, also, I believe, in parts of Colorado. I used it for years in modern NA engines, even doing some lighter towing, but always at higher elevations, so I think I was pretty safely on the lower risk side of your whiteboard. I assume the modern engine control systems adjusted timing to prevent knock, I never had an issue or heard any knocking.

[@geraldsahd3413]

one point- if your engine is Turbo or supercharged, do not use 85.

[@rockymountainjazzfan1822]

For many years, several state government agencies in the Rockies prohibited use of any fuel in state motor pool vehicles other than regular 85 octane fuel. If a state employee filled a vehicle with "super" or "premium" fuel, the employee would be personally charged for it.

[@grimreefer4366]

85 is standard here in most of Colorado. Only out east, almost to Nebraska or Kansas, have I seen 87 as regular. Running from 5000 to 10000 is what we usually do here. I can see if you go to low elevation, but you'll likely have to fill up at a place that only sells 87. I run 85 all the time here, and have no knock. Plus I drive my car hard. It's not turbo or super, but OEM calls for 87. I notice no difference between the two. Only people in the front range that need 87 probably need 91 instead. Dirt bikes and sports cars.

[@jamesowen150]

@@grimreefer4366 I used 85 in Colorado in my twin turbo Taurus. Would easily do 130 stock at 9000 feet. Went on a trip to Nebraska and the ignition retarded so much I couldn’t do 110. Ended up switching to a custom ethanol blend/tune. Then I blew it up do to poor maintenance. I guess if you use cheap gas you probably shouldn’t have a performance car.

[@EverythingisFire]

I moved to UT from CA earlier this year. Had never seen 85 before & liked that it was cheaper 😂 Went back to using 87 or 88, though.

[@bassmasta9117]

Interesting. I had my car tuned to a stage 1 93 octane tune and the tuner told me "don't get crappy gas at Wawa, make sure you get good gas at Shell or Sunoco" and I have been intrigued by this ever since. I never knew there was even a difference.

[@NG-VQ37VHR]

Yeah, I have a 93 octane tune as well on my VQ37VHR. I also use a weak octane booster with my 93 every time I fill up, just to be sure I don't run into an issue of bad gas and risk knock or switching to a hi-det fuel map, robbing me of performance.

[@mark8200]

You deserve to ride a bike forever

[@JavoCover]

@@NG-VQ37VHR Wow you better take care of your investment, that engine is no cheap. What is the factory octane rating for that engine?

[@donrandall49]

You probably have gas being sold under at least six different branded labels in your area. Do you have six different refineries in your area? I'm guessing the answer is "no". In other words, most everywhere you go, all the gasoline at all the local stations will be from one and possibly even two... possibly, but unlikely, even three... different refineries. Here in Denver, we have two refineries. All the gasoline (with rare and unlikely exceptions) will come from one of the two. The cheap gas at one station probably came from the same refinery as the expensive stuff across the street.

[@njsongwriter]

Yeah, I'm pretty sure Wawa is not top tier but the other two are. If you use ethanol-free fuel, WaWa has it but it's over-priced.

[@andrewallen9993]

My VW splittie will Run happily on 77 octane and it's older brothers on 70. A 7:1 compression ratio or less and manually adjustable ignition timing helps!

[@dabj9546]

In Germany we have 95 as the normal gas and 98 as premium. Edit: Just learned about the different scales from your little note. Seems to be 91 normal and 93 premium in AKI.

[@JakkeJakobsen]

91AKI is still far above 87AKI. 95RON is what we call regular in Europe, 98RON is Premium. 87AKI is crap for many modern engines, especially turbocharged engines. I've even gotten knock on 95/91 on a stage 3 Volvo S60.

[@enicaeduard]

@@JakkeJakobsen what do you expect, to run smoothly in a tuned engine

[@mag1vl]

Hello Jason from Australia :) A very well written and videoed article I enjoyed it thanks. Just for anyone who's interested we have - Standard unleaded petrol (91) - Premium, 95-octane unleaded petrol and Premium 98-octane unleaded.

[@marumiyuhime]

sweety the us uses a diffent calc than aus

[@charmio]

Sigh... yet another measurement system that only the US is hanging onto (well, also Brazil and Canada). Sometimes I wonder if they do it just to annoy tourists. For reference, most of the world uses RON (Research Octane Number) while the US uses AKI (Anti-knock index). To confuse tourists further it's often labelled on pumps as "(R+M)/2".

[@arthurgordon6072]

Same here in New Zealand.

[@Flies2FLL]

I've never seen 85 octane fuel. And I cannot remember an owners manual that would allow it. Great video!

[@11lizgoodall]

We have it in Colorado, at least where I live at 8500 feet. It's what I put in our F250.

[@DJR5280]

85 is at every station in Denver

[@volvo09]

@@11lizgoodall yeah, itcs only for elevation. Residents have no problem running it. The problem would be filling up and going to sea level and driving hard.

[@amorton94]

I don't think I've seen a station in CO that didn't have 85. If we have any, I'm sure you can count how many of them there are with your fingers. Unfortunately, our 85 is the same price and everyone else's 87.

[@TimkaD736]

85 at every station in Colorado Springs, Denver and other nearby cities. There are a few places that does sell 93 as well (8th and Kipling) I don't remember where others are at lol.

[@mattkovacs2732]

I owned an '85 full-size Ford Bronco with the 351 Windsor engine when i lived in Detroit Michigan. I actually got the owners manual even though i bought it 10 years old. In that manual, it stated that the 351W was designed to run on the lowest octane fuel available. The local Speedway gas station sold 86 octane and that engine loved it! One day i felt like giving my truck a higher octane fuel and that gave my engine spark knock that lasted about a month before i found the solution (which i can not remember). This truck was running a 650CFM holley carb (that was junk...buy edelbrock) and got 4 mpg no matter where i drove it (city, hwy, 4x4) so i was happy to spend a few pennies less per gallon. Of course this is when 87 octane was between .89 and .99 cents per gallon.

[@rodri_belo]

Ford should give him a shout out for his work! Great video as always!

[@themikeroberts]

I don't think it's necessarily positive for Ford, it raises awareness that their warranty is voided for using the gas that almost everyone uses at high altitude.

[@Kraigmire]

Won't a turbocharged engine have this issue at any elevation if you give it adequate throttle? The turbocharger will boost the manifold pressure beyond sea-level's pressure even at higher elevation, so that engine could experience knock at any elevation with lower octane fuel. This is why most turbocharged engines require premium.

[@danbert8]

That was a bigger problem with engine management that didn't measure or limit boost well. Modern turbo cars basically limit your boost to prevent knock and that will be true regardless of the atmospheric pressure. If say your boost is limited to 17psia on 87 octane, it will limit it to that 17psia regardless of if it's adding 2psi at sea level or 7psi at 10k feet. That's why most modern turbocharged vehicles "recommend" premium, but only require 87. You can make more power on higher octane fuel, but the engine will run just fine on lower octane fuel at lower boost. Personally, I stick with the 87 octane fuel because in my market it's 20-30% more for premium gas than regular and you're looking at 5%ish gain in power and even then, only at WOT.

[@Kraigmire]

@@danbert8 That's pretty cool. This must happen as a reaction to detecting knock though, correct? The computer can't know what kind of gas is in the car and therefore what the boost limit should be, so it can only back off the boost once knock is detected?

[@danbert8]

@@Kraigmirethat is correct. Modern cars have knock sensors that can detect the limits of pre-ignition and pull timing/limit boost to prevent engine damage.

[@Tagawichin]

I had a 2002 supercharged xterra. 92 or better was preferred, but lower octain was ok. The lower octaine gave significantly less performance but caused no harm.

[@andrewt9204]

@@Kraigmire Modern knock detection is pretty bonkers. The older method was to use what was essentially a type of microphone tuned to the frequency of knock and was bolted right to the block. I don't remember all the details, but modern engines use the spark plugs to measure the impedance across the gap to determine if cylinder pressures are too high. Something like that anyway, pretty interesting that engines can now adjust for knock on a per cylinder basis rather than just "listening" to the whole block.

[@peterfernandezjr5914]

I've actually seen this gas at a couple of local stations in So Fla and this is no high elevation place. They call it economy regular.

[@BareRoseGarage]

Here in ID we have a saying, "go kick rocks" (a nice way of saying F-off). A friend of mine from FL told me that saying was illegal there because they got tired of moving the "highest peak" marker.

[@volvo09]

Really?!? In florida?

[@grampy2004]

It maybe E85 that you are seeing which is 85 ethanol but i would not put it past the gas companies to try that ; )

[@peterfernandezjr5914]

@@grampy2004 No, those nozzles are different, these are brands that have a large range of octane available, from 85 to 93. I think it's all BS, they just mix them up. You wonder what you're really getting.

[@grampy2004]

@@peterfernandezjr5914 I know wish there was a way for the average guy to easily test to see what we are really getting ; )

[@eriknervik9003]

Years ago I took a road trip from Washington state to the Midwest and driving from Idaho to Utah I refilled my tank with “regular” fuel that was 85, I noted the 85 and thought it was wierd but I got it and kept driving. An hour later a warning light for the emissions control system lit up on my dash, I had never seen that light before or after come on, an hour later I got to the next truck stop and topped off with premium (91) the light went off and since then I now make sure to pay attention to that when I’m taking a road trip

[@raymondwest1973]

I live in Salt Lake (approximately 4,500 ft. elevations). I used to used 91 octane fuel thinking I was doing a good thing for my car. After I plugged up the second catalytic converter, it was explained to me why using premium at this altitude is not only not beneficial, but can also be harmful. I my engine could not burn the higher octane completely. So, I was putting incompletely burned fuel out the exhaust. I switched to 85 octane and have never had any problems.

[@mikej238]

just use 88,

[@shackti1699]

I'm in Utah as well, and have had no issues running 85. We live at high altitude, so it's just fine due to the lower oxygen levels here. Now, if you ran 85 octane at sea level, you might have some issues.

[@rightwingsafetysquad9872]

Use what is recommended by the manufacturer. Running slightly lower octane probably won't cause knock, but could. Running higher octane probably won't foul a cat, but could. Running higher octane than recommended will never provide any benefit under any circumstance with the possible (possible, not likely) exception of towing near a truck's capacity up a steep hill for a prolonged time.

[@rah4822]

Have lived and driven in higher altitude states for over 30 years and always burned 85, no knock, no engine problems. When I drive down to lower elevations I always fill up with 87. The real irritation is 85 is priced the same as 87 at lower elevations.

[@natejohnson5393]

@@rightwingsafetysquad9872I live in Utah and have been using 85 octane for 10 years, never had any knock or engine issues

[@Quantalume]

Interesting that Ford recommends 91 octane in their gas trucks. That makes running a diesel actually cheaper in most locales, including the DEF.

[@speedandstyletony]

Also interesting is the thumbnail for this video since the nozzle is green, ie diesel!

[@Madcatcon199]

damn bro im in chicago and diesel is almost high as premium! 4.45$ premium like 4.15$ for deisel

[@Dan_Neely]

It's mostly a recommendation for towing since that's about the only time you're going to be running your engine near max power for longer than it takes to merge onto the highway. And if you're doing a lot of towing you want a diesel anyway.

[@nathan00campbell]

@@Madcatcon199 im a self employed truck driver. Those prices are why i will not do business in blue states. The rest of the working class should jump on that same bandwagon until they figured it out. Just topped off my freightliner here in tx at $2.69 per gallon and even that is ridiculous

[@IronNam]

Random story concerning 90 octane in a 11.3:1 CR car with DI and dual VVTi(E). I refueled my ISF with 90 octane when I was stuck in the middle of nowhere Texas. My car's Knock Control Learning Value (Toyota thing) was reading roughly 15.0 - 15.3 (15 is baseline, so the car was NOT happy at all). For comparison, KS Costco 91 gives me ~20-21 KCLV (excellent!) and CA 91 ACN gives me 16-17 (trash fuel!!!). It was going to be a couple of hours on the highway until the next stations that have 91, but I was certainly looking for ethanol. The ISF's ECU doesn't read ethanol but can read knock levels of whatever fuel is in the car. Safely, one can "blend" up to 30% ethanol in the ISFs. This was a bandaid for those with Lexus F cars in CA because it mimics what a real 91 or 93 octane could provide. The ethanol raises the knock resistance but only up to 30% is what the ECU, injectors, and math wizardry can handle. For the next hour on the highway until I was somewhere in Oklahoma, I was able to sneak a couple of gallons of 91 octane in the car. It barely nudged the KCLV level to somewhere 15.5. Until I made it to OKC a couple hours later, I was babying this car at 60-65 and ensuring I was monitoring the load (viewable in my BT OBDII reader connected to my phone). Once I got to OKC, there was a specific station that sold ethanol and race fuel. Usually I would opt for the ethanol but I recall grabbing the race fuel. It was at least 100 octane lead free and I only needed a couple of gallons to raise my overall octane. Got back on the highway and my KCLV was a solid 22-23. I can't tell you how nervous that drive was and how relieving it was to finally drive normally, especially with traffic. With that being said, if I were to ever do such a trip again, I think I will carry a 5gal jug of E98 in case I needed to bump up my octane.

[@TestECull]

lol. You need a better car.

[@IronNam]

@@TestECull you need a better response

[@SeranaKnight]

Seriously, even the toyota manual states tat 92 is an option and to research it. High compression and engines with turbo or direct injection should use high octane or at least use octane booster and an additive.

[@sjsz06]

Use of abbreviations makes this hard to read. What the hell is ISF? Or KS Costco, KCLV, ACN, BT etc. I understand OKC because I used to live in Oklahoma. An explanation of the abbreviation the first time it's used would go a long way toward making your posts more readable.

[@brnmcc01]

@@sjsz06 Lexus IS F.

[@shackti1699]

I live in Utah. With the exception of one vehicle which required premium, I have always used 85 octane and have never had an engine knock because of it. I occasionally drive from 6,000 to 2,500 feet and back with the same fuel without any problems. I've ran both old and brand new trucks close to 10,000 feet also on 85 with no issues whatsoever. Altitude matters, and 85 is fine to use where it's sold. It isn't a scam, it's not a big conspiracy to destroy our engines here, it just works, and it works just fine. There really isn't anywhere you could reach sea level on one tank where 85 is sold, so it really isn't that big of an issue as people say.

[@flightmedic7634]

I've only used "Regular" unleaded 85 for the past 10 years or so ever since I have lived in Colorado and Wyoming with no problems but after watching this I don't feel quite as good about it. Luckily I live in NE Wyoming now where "Regular" is the way it should be and is 87 at most stations.

[@tomzphone]

This is what the manufacturer says about my cars, "Do not put anything lower than 91 or it can cause serious damage to the engine. " I have been putting the cheapest/ lowest octane gas I could find ever since the car had 40,000 miles on it. Currently I am just short of 290,000 miles and the engine runs no different than when it was brand new. The second car I have is currently at 105,000 miles and only got the better grade gas for the first 30,000 miles. And also runs no different than when it was brand new and I drive the piss out of these two cars. The third car is at 56,000 and no different.

[@REDMAN298]

I used 85 in an `87 Saab when I went out west years ago. I ran great. I was confident knowing the knock sensor would work things out. Knocking is scary when you think about the pressures going on by that piston.

[@ctbrahmstedt]

THANK YOU for this. This has bugged the hell out of me ever since moving to Colorado. Every one I know here driving a modern car still sticks to putting in 85. When I moved here from sea level, I was pulling a trailer and accidentally put in 85 - I've never felt more of a power drop in my engine output. From being able to cruise in fifth to having to almost drop down to third gear. Refueling with 87 gave me my power back. I was driving a '13 Wrangler, I'm assuming this reduction in power output was due to the knock sensors and retarding my engine timing. Do you think there could be long term consequences for putting in 85 at elevation for the lifetime of a modern vehicle?

[@rockymountainjazzfan1822]

In my many decades of experience driving hundreds of thousands of miles at high elevation, no. Don't confuse loss of power necessarily with 85 octane. A naturally aspirated engine will lose 2%-3% of its power for every 1,000 ft. of elevation. 87 octane might help power marginally under very high load conditions, but the elevation itself is the power sapper. Also, somewhat counter-intuitively, most cars will get better fuel economy at high elevation because the fuel injection system leans the fuel mixture to compensate for the less available oxygen at high elevation, so, less power, but also less fuel consumption. The last time I had a vehicle knock at high elevation with 85 octane was a late 1970's carbureted vehicle with no electronic ignition.

[@Riley8425]

@@rockymountainjazzfan1822 buddy modern cars leaning out the mixture to adapt to the lower air density at high altitude is exactly why modern cars are prone to knock with 85. Yes you are right about the loss of power at altitude, but the jeep was almost certainly detecting knock and pulling timing like crazy as well.

[@ceremyjlarkson9475]

That's correct, it most likely had a knock detection system or an octane detection system. As it saw you got less and less air, it probably ran kinda of okay at high altitude. But once you got lower, it immediately declared knocking and went into safe mode to prevent serious damage.

[@ze_ep]

I've been putting the lowest grade (usually 85) in a Colorado 2015 Mazda 3 for years. Higher octane = better mpg, but I don't notice any performance difference on the front range.

[@patrickjeter7928]

Been using 85 in Colorado for a decade in things like accords and acura rdx... No discernible difference or issues for me.

[@sagehiker]

As a retired pipeline terminal operator in motor fuels, regular unleaded gasoline was treated as a bit of the garbage dump, with off spec product including distillates, product interfaces , and water was diverted to regular gas tanks. Note I was in an low EPA attainment area where the standards were looser and no state regulation. Agriculture subsidies for ethanol have really wrecked product quality.,