Who's Got Better Fuel? Octane Ratings Explained and Mythbusted

So what is the octane rating of fuel? The octane rating of fuel is actually an indicator of just one single thing and that is the fuel’s ability to resist detonation or knock. That’s it. The octane number has nothing to do with the energy content of fuel nor it’s impact on the power output of the engine.
The octane rating is also only relevant for gasoline engines because gasoline engines compress air and fuel together and then ignite the compressed mixture using a spark plug. When we compress air we we bring the air molecules closer together causing them to bump against each other more which then increases the temperature of air. And if we compress it enough to raise the temperature enough this can then lead to the spontaneous ignition of the air fuel mixture which is independent of the action of the spark plug. This spontaneous ignition of the air fuel mixture is also known as detonation or knock. It’s an uncontrolled event which can damage the engine if it’s strong enough or persists long enough and hence must be avoided.
So if your engine requires let’s say regular 87 octane fuel and you put in premium 94 octane in it simply means that you’ve increased the knock resistance of the fuel inside your engine. but this does nothing because your engine is designed for 87 octane and wasn’t knocking in the first place. In other words you’re increasing protection against a non-existant risk. The only time when a higher octane might have helped is if there was something actually wrong with your engine which was causing it to knock. Your ecu detects the knock through the knock sensor and then retards ignition timing to stop the knocking which reduces engine performance. You then pour in the premium fuel which prevents the knocking and your ECU restores normal timing. In this case the higher octane fuel didn’t give you any additional performance but only restored original performance by acting as a band-aid fix for the fault inside your engine. In fact on most modern engines this scenario is impossible because knocking would trigger a check engine light or even limp-mode and engine performance could not be restored without resetting the codes regardless of the fuel you put into the engine. The reality of things is that putting in high octane fuel in a normally operating engine that doesn’t need high octane fuel actually reduces the performance of that engine. And this is because a higher octane number doesn’t just increase knock resistance, it also usually leads to a lower flame speed of the combustion and this can lead to reduced performance.
Now diesel engines don’t have spark plugs and they only compress air which means that the octane rating is irrelevant for diesels. Diesel engines introduce fuel into the combustion chamber only when the air has been compressed sufficiently to be hot enough to ignite the fuel. This is why the tendency to self-ignite under heat and pressure is actually desirable for diesel fuels and the reason why they use a completely different rating called the Cetane number which measures this.
So how is the octane number of fuel even measured? Well it’s measured using a special machine which is essentially a little single cylinder four stroke engine, as you can see here’s the cylinder and here we have the valve springs, but what makes it different from real engines is that it has a variable compression ratio.
The compression ratio of the engine is the ratio between the largest and the smallest volume of the cylinder, in order words it’s the ratio between the total cylinder volume when the piston is at bottom dead center and when it is at top dead center. The compression ratio of an engine is fixed and can’t be changed when the engine is running. To change it you have to take the engine apart and make mechanical changes to it’s internals to change the compression ratio. For example installing a piston with a large dome is going to decrease both the smallest and the largest cylinder volume leading to an increased compression ratio.
The higher the compression ratio the more we compress and heat up the air fuel mixture leading to higher chances of knock. This is why high compression ratio gasoline engines need higher octane fuels. Another important factor is the presence of forced induction. A turbo or supercharger also compresses the air and pushes it into the engine which means that forced induction also contributes to increased air temperatures and increased chances for knock.
So the compression ratio of a real engine is fixed but it’s not fixed for our octane rating test engine. Older versions of these machines featured a manual handle which raises or lowers the height of the cylinder head thus changing the compression ratio of the engine while it’s in operation.
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#d4a #octane #gasoline

[@d4a]

This video is available with French subtitles, thanks to a generous contribution of my friend Sweet Ninja Support d4a: driving-4-answers-shop.fourthwall.com/ D4A merch: teespring.com/en-GB/d4a-merch Patreon: www.patreon.com/d4a

[@freyja4954]

Your a bit off Many modern engines actually have a high end low octane table you will switch between one and the other if the knock sensor sees knock if it continues to see knock once it switches to the low octane tit able for the Ignition timing it will then go in the limb mode. My BMW is a classic example of this. This was even shown back in the 1980s on forge Thunderbird Turbo coops where they actually had a premium and regular switch on the - and it would control 2 different spark tables.

[@raoulrr]

"higher octane does not give you better performance" is totally wrong and misleading. There are plenty of cars (from Mazda, VW, BMW etc.) which come from the factory with different power ratings for different octane fuel (lower power with lower octane, higher power with higher octane). If you've ever tuned a turbo engine you'll know all about engine maps dsigned for a specific octane fuel or ethanol blends. Higher octane (or e-blends) allow for more advance timing, which in turn equals more performance. ..so "myth" NOT busted, until you can get BMW or VW to write a retraction :)

[@grndragon2443]

What about a different view? using higher octane when doing a lean burn to try to squeeze more milage.

[@m.benylazar3648]

Can you please add the table in the comments. Thank you sir for your time and effort put in these videos.

[@danielhristov6175]

Omg I’ve never been so wrong in my life. I always tough + octane = more knock xD !!! Question: do octane number degrade in time? Like, if I put 98 octane and leave the car in the garage for 3 months does it become say 97 or 96?

[@SubRoseaStudio]

higher octane fuels also taste better. I hate syphoning 91 RON, it tastes worse than vegemite.

[@Ballacha]

not surprising considering only a handful of things on earth taste on par with vegemite.

[@FishTurd69]

Mate, Vegemite is a DELICACY

[@loddude5706]

Strong stuff Vegemite, one & only reason the upside-down people get good at cricket : )

[@tomr6955]

@@loddude5706 Love me some Vegemite, fuel of champs

[@andrewcannon587]

toluene and xylene taste better than regular alkane

[@lc1565]

As an American, I will always increase my protection against nonexistent threats.

[@chiefdenis]

🤣🤣🤣

[@woofywooflez384]

Get this dude in congress now

[@walliisch]

You should have touched on the etanol levels in the diffrent kindes of fuels. In Sweden we have 10% in our 95 and 5% in our 98. Or make a dedicated video because EU has set a minimum of 10% etanol and this raises a lot of interesting questions. Especially for older engines. Keep up the good work

[@higbeedoug]

Is your etanol the same as our ethanol here in the states or is this a simple typo? en.wikipedia.org/wiki/Ethanol

[@walliisch]

@@higbeedoug Yes

[@wilianamaral]

ethanol is a modern aditive to prevent detonation on gasoline since lead aditives were banned. the downside is that ethanol can corrode aluminium parts and react with some kind of rubber used on old engines. in a nutshell you could say adding ethanol to gasoline is a way to increase the octane rate. Brazil has 25% ethanol mixed in the gasoline. You can buy regular, additive (with more detergents) or premium (95-99 octane but usually ethanol free).

[@walliisch]

The question is how bad 10% etanol is for an older engine not designed with etanol in mind. Like you say rubber gaskets and such. I pay a little premium and fill up with 98RON 5% etanol on my old outboard engine. All other gas is at least 10% here.

[@curtisjmurphy]

Should also be noted that ethanol will break down faster than pure gasoline, so if you are filing a infrequently used engine (lawnmower, boat, generator, etc.) Or if you are storing a reserve of fuel in a gas can it would be a good idea to spend the extra couple of bucks on ethanol free premium fuel.

[@jonathansmith7306]

This explains the difference between Europe and US octane numbers really nicely. I was surprised that Audis require 95 octane, but it makes sense that it actually means 91 in the states

[@izgrevski056]

which is the premium fuel in US and here in EU is the regular ;)

[@chickenfishhybrid44]

​@@izgrevski056premium in alot of the US is 93. In my State it's 92. It's 91 in California for example, it can vary by state. Some stations in the US have 110 on the pump, E85 etc.

[@drunkasquadronweflytogethi4822]

still the best automotive youtube channel in my opinion! Best possible explanation you can find in the whole internet I think. Perfectly presented, clear speech, exceptional technical knowledge, paired with a healthy amount of humor, an no bragging, and no nonsense or myths sponsored by God knows whom! Wonderfull my friend, love every single video you made so far! keep it on! Greetings from Austria!

[@LevisL95]

Indeed!

[@MrHanswurst47]

Auch ein Österreicher! ;)

[@jayr6637]

Those impressions, especially that American accent were far from clear speech... I have no idea what he was on about! But the rest of the video was very clear :)

[@bigbodykarate6403]

but he is wrong on this one

[@milosozegovic6980]

Even though the Europe octane number is higher for the same fuel than in US, based on the video if eu 95 = 91 in us, we got higher octane fuel here. The thing is that you cannot buy anything less than 95 here in EU, but in US you got 87 which would be like a 90 in EU (according the the table in the video).

[@Bob.Seishin]

there are many station has 98 or 99 too not just the regular 95 with e10 or e5, but they are fukin expendives nowadays.... :D

[@chrissimmons9969]

In some western US states like Colorado they have gasoline with an octane rating as low as 85.

[@Thatdavemarsh]

@@chrissimmons9969 I believe it is because of the thinner air at altitude.

[@Bamsebrakar2011]

I believe you can still buy 92 octane fuel in Europe at some petrol stations.

[@nirfz]

@@Bamsebrakar2011 Not so sure about that. In central europe for example you can find "91" on some fuel stations price thingy and a nozzle for it, but it costs the same as 95, as it is actually 95. It's mostly older fuel stations that have not yet been renovated and the 91 labeled parts removed or relabeled. The raffineries here (like the ones from OMV for example) don't even make anything less than 95 anymore. (Hence the same price for "91" and 95 on the few stations that still have labelled "91")

[@ClickLikeAndSubscribe]

This is a fantastic all-in-one summary of all the questions that other explainers leave open. Nice to finally have it all pieced together!!

[@TheDude50447]

generally the fuel is the same. Its just a different measuring system. Though some engines can advance the ignition timing with higher octane fuel than what theyre rated for which increases power and/or fuel economy. Most modern engines can retard the ignition timing with lower octane fuel than what theyre rated for in order to prevent engine damage. General rule is: Whatever it says in your car manual which fuel to put in is the fuel to put in.

[@slycarlo8747]

Yup all Silverados past 2014 have this technology.

[@warrenpuckett4203]

Does not explain why my old '88 LSC got 15 MPG in California and 19MPG in Texas. Both are 93 octane as required in the owners manual. Could be the TEXAS blend had less alcohol mixed in? Say 10% less ? No I did not change the timing. BTW I went from a refinery job in CA to refinery job in CA. The difference between fuel stops is noticeable. If you use cash.

[@TheDude50447]

@@warrenpuckett4203 could be all sorts of stuff. Maybe very different altitude maybe more Ethanol content as you said or maybe you just drove differently. Like maybe you had a lot more City traffic at one Place but im just guessing. Also im no expert.

[@johnnyblue4799]

@@TheDude50447 Legal speed limits are higher in Texas. I think the ethanol is the issue.

[@kevin122759]

@@slycarlo8747 I run premium in mine. Not sure it is worth it or not. I average 23 mpg highway.

[@Nando870s]

Great video! i got tired of explaining to friends just what you said in the video. Another misconception i hear a lot is about ethanol making more power than gasoline Ethanol actually has a lower energy content than gasoline, so if all things are equal, it either makes less power, or takes more fuel to make the same power What actually makes more power is the higher Timing/Compression ratio/boost that ethanol allows you to run in relation to gasoline.

[@Carlos.Rivera]

Then you got more power and move the vehicle "effortless", why still worst on fuel economy?

[@jamesd2863]

If a vehicle has the capability from the factory to run e85 it is possible to make more power than gasoline without any other modifications. The reason is that the spark table will change based on conditions and input from knock sensors. Less knock and colder combustion means more spark advance

[@Nando870s]

@@Carlos.Rivera because, like i said, ethanol has a lower energy content, to make the same power, you must run a richer A/F ratio, you are always using more fuel to move the vehicle irregardless of the power it makes in relation to gasoline.

[@Nando870s]

@@jamesd2863 yeah, that's why i mentioned timing. In Brazil most cars are flexfuel, and make around 3-5 more HP when running E100 than gasoline (actually E27, not pure gas)

[@chickenfishhybrid44]

E85 fuel for example has an approximate octane rating of something like 114 and also has colling effects. Ergo you can generally run more timing and boost with E85 fuel than standard gasoline. Even though you will be using more volume of fuel, at the price and availability at many pumps it can give you comparable performance to race gas and cost less and be easier to get.

[@doicheman]

Always the best automotive channel with clear and precise explanations, but acting? I was not expecting that! This is as good as the greeeeen screen shenanigans. Congrats and once again, thanks for the video.🏆

[@jaredkennedy6576]

Some manufacturers have played around with variable compression engines, and we may see more of that as emissions and economy standards tighten. For now, a similar effect can be achieved with variable valve timing being able to transition from Otto cycle to something like a Miller or Atkinson cycle.

[@ryanhorsley9965]

I worked as a fuels chemist for years. This is a good and simple explanation of octane number and thankfully does touch on the R versus (R+M)/2 methods for certifying knock performance. This is what misleads Europeans into thinking that their fuels might be "better". In reality, the American specification is harder to meet due to averaging motor octane into the rating, where the "M" is the anti-knock performance under load. Also, octane rating is only one data point among many in certifying a finished fuel. I recommend comparing ASTM D-4814 to whatever the equivalent European standard is for a more comprehensive comparison.

[@cossiedrifter]

Apparently many tuned cars imported from Japan blows up when American fuel is used. So there seems to be some differences in fuel quality between countries.

[@nagyandras8857]

Erm.. The regular fuel of USA is 87 or ron 90. In europe the normal is ron 95. We do have better fuel. Just sayyin.

[@DoritosGoBrap]

@@cossiedrifter also, every one of those cars are 20-25 years old with 30k miles. Nobody wants to open, clean and re-seal before restarting and it just dies.

[@aceofspades9833]

@@nagyandras8857 far from it buddy get your facts straight your guys regular is on par and the same as our regular, remember we all get our gasoline from the same place it’s just rated differently

[@nagyandras8857]

@@aceofspades9833 yer regular is ~ron 92 at best.. our worse is ron 95. that simple.

[@ralfhtg1056]

Thank you a lot for this informative video! The prejudice that the US uses inferior fuel keeps persisting strongly here in Germany.

[@davidhollenshead4892]

For inferior fuel, in rural Mexico cheaper 80 octane fuel used to be common. However, low compression engines with the timing retarded would run fine on it. Which is why the air cooled VW's and older American cars were popular as both had low compression engines...

[@ralfhtg1056]

@@davidhollenshead4892 interesting. Here in Germany 91 ROZ fuel was abandoned completely by 2008. 95 Octane is standard since that.

[@Roarman57]

Yep that’s what all Americans look like but you forgot to say y’all.

[@Thatdavemarsh]

Fantastic content as always. Well researched and presented. Thank you!

[@guyhasd]

Excellent video that answered many questions I had. Thanks.

[@LevisL95]

Aren’t many of the new engines adjusting ignition timing depending on fuel? I remember hearing different power figures stated by manufacturers for "regular" vs. "premium".

[@LevisL95]

I think this was the case with Mazda at least.

[@dancancade7101]

Only if the engine is supposed to run on premium. Running such engines on regular can cause pre-ignition which will cause the knock sensor to send a signal to the computer to retard the timing, which will result in a loss of power. It could also possibly lead to engine damage. Use a fuel with the level of octane recommended in the owner's manual for the vehicle. Nothing more, and nothing less.

[@HeadsDisplay]

@@dancancade7101 nothing beats when poor fools put gas in a diesel engine Note got a cam am spyder recommend fuel is 97 USA so am left with using 93 all the time

[@chickenfishhybrid44]

​@@dancancade7101 That's not necessarily the case anymore. Various manufacturers will say you will get peak power running premium, say 91 octane, but the car is still able to run 87 octane safely.

[@dancancade7101]

@@chickenfishhybrid44 if "peak power" is obtained by the use of a higher octane fuel, then that’s what the engine was designed for. Either the engine has higher compression or it's supercharged/turbocharged and the use of a fuel with lower octane will result in the computer adjusting according. What's the point of buying such a vehicle if the plan is to run it on low octane and never get the level of performance that you paid for?

[@nox_chan]

As a Texan, I can confirm we talk like this.

[@t.s.racing]

And ya'll have the best dang steaks anywhere in the world ! My bikes might run on premium, E85, or C16, but I run on Angus !

[@kengarcia1461]

Learnt something that I never knew about today! Thanks again Mr D4A!

[@WONMARK]

This was awesome to watch. Entertaining and educative. Thank you...

[@zweispurmopped]

Excellent! You'd fit into the mid western state seamlessly, man! 🤣 Some 25 years ago, I was working at an airfield. One day a jerrycan with some 10 litres of Avgas, 150 octane aviation fuel, was left over. As my Volvo 244 had no catalyst yet, I was the lucky one to win free fuel that day, yay! 🤗 There was about 15 litres of 95 octane in the tank left when I poured in the Avgas. I had never before heard my trusty old Volvo run _this_ smooth. Like a V12, like a turbine! That being said, the B21E engine was a rather gentle character to begin with. That was a very very lovely car indeed!

[@errrytangraysiss8083]

When you try to be a bigot yet, have no idea what you're talking about. Hahahaha!

[@paulg3336]

The engine's ignition timing was wrong , there was a cooling system problem or the cylinders had severe carbon deposits,if what you say is true. They are the only diagnoses that can be deduced from what you describe.

[@zweispurmopped]

@@paulg3336 Nope, the engine was enjoying best health. Back then I didn't have the knowledge to check such things myself, there was a retired mechanic living next door to did such jobs for small money. Brilliant lad, he knew 100% what he was doing. As I didn´t speed with my 244, I did obviously not have a chance to notice any performance differences, but I did notice that the engine sound changed and the bugger felt more gentle in general until I put fresh 95 into the tank the next time.

[@Haaraff]

I can't get anything lower grade than 95 RON in Switzerland, while regular in the US is ~90 RON. I tend to use 98 octane in my motorcycles (95 octane contains up to 10% ethanol which is an issue for my models) and in my "other" car which specifically requires 98.

[@ScottRipley]

In the US, it varies by region. In most of Texas, you would get 92 RON equivalent, somewhere like California will be lower, and Northern New Mexico starts at 88 RON equivalent.

[@v8rumble123]

This correct. EU 95 (91 NA) is often minimum, where in NA 94 (98 RON) isn't always available. NA has a lower availability of Premium fuel.

[@ua1054]

Ya we simply don’t have “regular” in Europe and the lowest is “premium” 95RON / 91AKI

[@afox5319]

@@ua1054 yea premium fuel for keeping the working class poor prices. 98ron is 2.30 per litre in my country lol

[@v12-s65]

In switzerland we don't offer lower than 95 neither E10. Highest rating here is shell 100RON V-Power Racing, only germany has ultimate 102.

[@ryanv1807]

Thanks, you answered all my questions and then some I didn't even know I wanted to know.

[@michaeljoiner2503]

I have always liked your productions 😁 another great one!

[@michaelallen2501]

Some manufacturers (like Ford) will rate a car for 87, and rely on knock retard to keep it alive. The 3.5L V6 Ecoboost is a prime example of an engine that gets substantially better fuel mileage and torque output by running 93+ in the 87 rated car. You'd never catch me running 87 in a GTDI engine, regardless of what the manufacturer states. All of these claims I've made have been verified by thousands of ecoboost owners with aftermarket tuners and dataloggeers. It's pulling timing all over the place on 87. Get the OAR (Octane Adjust Ratio) above .95 and they come alive on the stock calibration. According to Andre at HP Academy, the Subaru platform also have an aggressive timing strategy that lives on knock retard, but on any pump fuel lol.

[@exoroxx]

I had a Ford Focus ST 2.3 Ecoboost, which was rated at RON 95 (91 octane in the US). I think RON 98 was just better and so that was always my choice (or better!), but once I made a test: Run with RON 95 (91 octane in the US) and give it some full throttle moments on the Autobahn. OAR was at .77 and the case was clear. Top speed died at 255 - way below the possible maximum - and it was thirsty, too. Later on there was another test: This engines works totally fine with E10 (RON 95 with 10 % ethanol), but you may not push that engine too hard. If you push it, you'll better have a higher octane fuel.

[@michaellorenz7177]

I've seen differences even on the 3.7 NA V6. Rated @ 306hp in Mustang spec, some dyno pulls have shown 12-18 hp increase just switching to U.S. pump 93.

[@misham6547]

Why then? Are they nuking their CAFE on purpose?

[@michaelallen2501]

@@misham6547 it's affects performance and longevity alot more than mileage. As long as it survives the warranty period nothing else matters.

[@misham6547]

@@michaelallen2501 but if you decrease boost and retard the timing you leave effeciency on the table. Ford could have gotten a couple more mpg on EPA and then wrote something like you can put in regular but premium recommend

[@dog-bite186]

Fantastic explanation of the sometimes mystery surrounding octane and whether higher octane leads to better performance. Thank you.

[@Kacpa2]

It actually does lead to better performance in turbo engines, they usually are recommended to run on 98 ron/93 aki and thats where they have their advertised power output in older turbo cars, but they still can run on on 95 ron/aki just fine, justbthat it will be will slightly pulled timing hence lower performance. Naturally aspirated engines CAN benefit from higher octane with engine mapping tuning and more aggressive ignition timing on 98 ron. So its not like there is no gains to be had from running higher octane, but it requires extra steps to be taken to actualy experience those with na motors.

[@valyarde3236]

Very good imformation I always thought higher octane increases performance, your topics certainly help take away the myth thank you very much, it all comes down to tuning and knowing your compression ratios awesome.

[@kawigoodtimesroll]

you're so talented in acting and fuuny in a hysterical way...great impressions i laughed my hat off 😆😆😆

[@dipanshubiswas890]

I actually never knew this...very fundamental concept and very very informative video...thank you very much 👍

[@kristianhermann5971]

Thanks for the video - I've always wondered this

[@zvonimirsic1952]

Al si skinuo Amere,svaka cast ! :D Oplakah Imam auto iz 2001god. i drago mi je sto sam pogledao ovaj video,ustedeo si mi novaca, hvala! :) Bome si detaljan u objasnjavanju, svaka cast!

[@ScottRipley]

While true for driving to the supermarket or normal commutes, I would add that there are exceptions to the more octane than recommended does no good rule. In extreme applications where heat build up in the engine is expected, a slightly higher octane than recommended can help. Example: towing with a gas v8. Most trucks in the US require regular gas, but premium can help eliminate knock in a heat soaked engine, helping with power and fuel economy. See also rock crawling, and drag racing. In drag racing a turbo 4cyl that required premium (93 r+m/2), I've had good results with mixing in no lead 100 r+m/2 to bring the average up as high as 95. Go beyond that the specific vehicle's requirement to keep knock in check in the specific application, and performance will begin to decrease. Also helpful on long climbs in high altitude mountains where the thin air reduces cooling.

[@markuscamenzind5510]

thin air reduces compression and temperature is lower at altitude basically the higher you go the richer your mix

[@paulsawczyc5019]

My old Harley starts to knock at idle in the summer - if I'm at a long red light.

[@Thatdavemarsh]

At altitude, I believe you need less octane. That’s why you see 85 in Denver. I get why you may opt differently in a fully loaded older engine that may have hot spots though.

[@ScottRipley]

@@Thatdavemarsh My specific experience with mixing 100 no lead from a VP station was low mileage high compression NA motor with direct injection that required premium fuel. I initially purchased the 2013 BRZ in Denver, and performance was deplorable. A VP station in Albuquerque NM with 4 gal of 100 R+M/2, and filling up at every 1/2 tank provided a record MPG on a trip from there to SLC, UT. 40-50% better than the trip to ABQ. I could feel the car reducing power after every fill. The performance was completely unexpected. The VP fuel was over $5 a gallon, which was insane at the time. It was about the same as the other 7+ gal of premium I put in at the same station. I still saved money over the entire trip because of it. If only I could get it for that now. I believe the octane ratings at high altitude are specifically for old engines. The distribution model was set up during the age of carburetors and distributors. Modern engine management can take advantage of the better fuels.

[@DpMario11]

*petrol -petroleum, liquid Gas, LPG, is a gas. America needs to really get on board with not being the only country to do something differently for no reason, especially as it's stupid.

[@nick4506]

in in college i had a combustion class and we had a big calobrated octane tester. gotta know that the difference between stations was more then the difference between the octane levels at the pump. ever since it leaves the refinery its continues to change octane as stuff gasses off. the cheapest gas did the best, probably because more people buy it and gets more turnover and has consistently fresher stuff. they also did the best for the lowest water content for the same reason. it was like valero that was above shell, chevron and the like. I've never had problems with ethanol in my old cars but maybe its because I get the cheap stuff that's dryer.

[@Born_Stellar]

ethanol absorbs water while gas does not, so it does provide some protection if water is an issue in your fuel. the issue with using it in older cars are the rubber components can get eaten away over time, its not going to effect the running of the engine. I've pulled the injectors from my jetta with 120k kms and the seals were in better condition than a car with only 40k, I only run 94 which up here in canada is required to not have ethanol.

[@nick4506]

@@Born_Stellar gas obsorbs water too all the time but in large gas storage tanks the ethonal drops out into the water sitting on the bottom. and when the water is drained away along goes the ethonol. and because ethonol is the primary octane booster now the gas has a lower octane.

[@xidarian]

Ethanol free gas is good for carburetorated engines that are going to sit for a while. Gas with ethanol can gum up your carburetor if it sits a while.

[@nick4506]

@@xidarian the gum is the oil additives the put In all gas. If you leave your peacock on and the bowls are continuly full and evaporating off what's left behind is the oil additives. it will gum just as quickly with non ethanol fuel as ethanol fuel. It reely doesn't do that mutch but people will blame all their woes on ethonol.

[@martinneumann7783]

Best ending ever! Thanks for explaining. Now I know more about the American way of knock resistance display.

[@Richard4point6]

Thank you for the understandable clarification!

[@Low760]

Australian 91 has 150ppm sulphur making it dirtier out the exhaust on top of being lower Octane. Definitely seen better economy with higher octane fuels on modern motors, like the timing increases once it works out it's not knocking.

[@mwjscn]

One of the cars I have driven specifies a minimum of 87 (R+M/2), but can go up to 93 as stated in the user manual. It delivers best performance at the higher octane ratings, since it can advance the timing before knock occurs and uses the knock sensor to bring the timing back if 87 is in the tank. So while it is mapped for and can take 87 octane, it does benefit from a higher octane gasoline in the tank. I think this is great since if you're on a highway trip you can fill up using cheaper 87, but if you want to do any performance driving you can still get the maximum out of a higher octane like 93.

[@Twobarpsi]

Exactly my scenario as well. In cold frigid winter I will use 87. Summer, AC on, 93. My car has adaptive timing and knock sensors. Great comment!!

[@FakeMichau]

@@Twobarpsi why 87 during winter? simply because it's cheaper?

[@Twobarpsi]

@@FakeMichau the air intake temperatures are so cold, less chance of detonation on my normally aspirated commuter car.

[@dmitrykhramov1832]

Thank you very much! Very informative and helpful! As always, super interesting…. 👌👍💪

[@stanza77]

Love this channel! Feel smarter just for having watched this.

[@Flies2FLL]

Higher octane fuel allows you to add a bit of spark advance. The actual amount of power gained is always less than about 5% in ideal situations, and typically it is negligible. If your car knocks on acceleration then use premium. If it doesn't then don't put it in; In any case follow the manufacturer's instructions.

[@johnhufnagel]

This is the reason why whenever possible, I try and run nearly dry the tank on my jeep and fill with 93 (US) before towing near max capacity for long distances. It doesn't allow the engine to make more power, but it does keep it making max power when pushing the engine harder, which also means I actually get a (1-2 MPG measured) increase in fuel economy on those long distance towing trips. I've made the same trip with the same load multiple times (track day towing) so I was able to verify.

[@raft5205]

Love the accents 🤣🤣🤣

[@TurboHappyCar]

Fantastic content as always! 👍

[@callmefoxie2950]

There is one thing -- higher octane also often has better additives to help clean the engine and valves (more so with indirect injection). Not always, but often it does. I sometimes grab a higher octane just to pretend and hope it cleans the engine better, and even if I grabbed a full tank (50 litres) it is close either $2 or $4 difference usually. Or some petrol stations offer normal "95 pro" which should have better additives, usually cheaper than 98 but ... your mileage may vary (literally) though :)

[@giggiddy]

I commented above before seeing your post. I do the same as I'm pretty sure premium has better or more additives.

[@infosneakr]

I'm not sure that is correct

[@d4a]

This is highly dependent on the brand of gas station. Some put more detergents and other stuff in higher octane fuels, others put the same amount in all octane ratings.

[@crissd8283]

This is certainly not always true. Basic additives are always included in all fuels. Additional additives are added by the station thus if you want more additives, the best way is to buy it yourself and add it to your tank.

[@littleherms3285]

The best way to get extra stuff is to buy a name brand gas. Going to Costco and getting premium is not going to cut it.

[@Kerleem]

Interesting video. I was just talking about this in my video on my imported Mercury Grand Marquis which I imported here to Europe. The caveat is that in the US, it’s customary to fill up with the standard 87 octane whereas here in the Netherlands, euro95 is the standard which is the equivalent of 91 in the US. So in my case, I am putting better fuel in it in the context of octane rating.

[@CynHicks]

Unfortunately using higher octane on engines that make no use of higher octane is a waste of money (here where gasoline is cheaper than octane additives) and can actually lead to efficiency problems. Really cool that you decided to import one those though. 👍

[@machdaddy6451]

Always entertaining and informative.

[@JohnChuprun]

Excellent video, thanks!

[@dafff08]

What if the fuel is so poor quality in certain brands, that only the premium high octane fuel lives up to the needed standard and thus the statements?

[@skurblord3401]

While I can't speak on the world as a whole I can safely say that Most places in the world have fuel production extremely well regulated and encountering "Bad gas" is simply not a thing anymore. Back in the 60s and 70s sure but modern day fuel is very consistent. Similar thing with motor oils ironically. The absolute cheapest oils today are better than most of the top tier oils from 30 years ago. In the US fuels are tested regularly and have significant fines for companies that fail.

[@fastinradfordable]

I enjoyed this. Learned a lot more than engineering school. I had hell owning a euro shop in USA where owners would assume RON numbers fit octane. Havoc ensued.

[@jreererer8490]

So nice of you that you also include diesel engines, most youtubers act like they don't exist

[@edthompsom9368]

Thank you....Some times I've noticed that R+M/2 on gas pumps but always forget to look up what it means

[@JxH]

In our region (Maritimes, Canada), the bottom two grades may contain up to 10% Ethanol, but the 'Premium' grade typically does not. So that's a factor that was not mentioned here. Your regional circumstances may vary. I recall that my 1986 VW GTI supposedly had adaptive spark advance, constantly advancing the ignition timing to just before the point of detonation. So the spark advance was governed by the fuel. Buying the best fuel (Sunoco Gold) made an obvious difference, and No, I wasn't just imagining it. Present vehicle runs 16 psi boost, so I'll take the best gas thanks.

[@Syncopia]

Only Shell as far as I know, esso and petro Canada and the lot still mix it in

[@Flies2FLL]

The spark advance on an '86 GTI is good for about 5 hp in ideal situations. So you went from 105 hp to 110 hp; I hardly think that would be noticeable. By the way, by turning your distributor about 5 degrees counterclockwise you can achieve the same thing, but listen for spark knock...

[@jayr6637]

@@Flies2FLL The 86 VW Golf GTI is very light, weighing under a tonne, so bumping power from 105 to 110hp would be noticeable! I've always drive small cars & in some cars I'd notice the power difference when changing the fuel filter or air filter :)

[@Flies2FLL]

@@jayr6637 Those weighed about 2300 pounds. I drove an '85 Scirocco turbo for 8 years, and one thing I noticed about the car was that a long drive on the interstate highway really made it run good the next day. It felt much "snappier", though I doubt it had any more actual power. A 5% change in power will be barely noticeable, if at all. Trap speeds in a quarter mile will show the improvement.

[@jayr6637]

@@Flies2FLL A buddy of mine had an 86 Golf GTI 3 door. His definitely weighed under a tonne, about 920kg... maybe they weighed more in the US due to regulations. Anyway, maybe it's because I've never owned a car weighing over a tonne & have always owned NA manual cars, but I notice small gains... especially on familiar roads :)

[@vince0815]

Im wondering whats the highest pump gas you can get in the US? Cause that could be comparible. In Germany for example the highest pump gas Rating you can get is 102 ROM which would be around 97 in the US. But you can actually get it all over Germany. There are a lot of gas stations where this is available.

[@Hardy_H_H]

depends on which state you're in. but premium falls anywhere between 91 and 94 octane. 91 where i live.

[@Sjef0194517]

I use that gas in my carburated racebike. Engine runs better in the high rpm range

[@steveapel2961]

Vincent Rohrig, greetings, around where I live( Wisconsin U.S.A ) you can get, although it's designed for recreational off road use only, ( I use it in my sportbike when I spend a day on my local racetrack) 98 octane (antiknock index RON+MON divided by 2 ), or just RON( I think around) 103 or 104 ( your system of measurement). This fuel also has 2 extra caviats, 1 It is true GASOLINE, that is it is Not ethanol and does not contain any alcohol, and 2 This fuel contains lead. Leaded fuel was phased out in the United States I think around the early 1990s because of leads high toxicity. Lead was introduced by Dupont corporation I think around 1920, as a means to boost octane ratings of motor fuel, as well as being a lubricant for valves. Also, this fuel can NOT be used in the majority of road vehicles because the lead will in short order destroy a car's catalitic converter. I can use it in my old zx7 ninja safely since the bike has a race pipe on it and is sans catalitic converter. By the way, you are very blessed to live where you do, as a longtime somewhat knowledgeable Motorsports fanatic I realize your general populous are FAR higher skilled drivers than the lacidasical drivers here in the states. Just curious, do you by chance live near a derestricted portion of the Autobahn?, If so how often do you see exotics and hyper cars flying by in the left lane at, oh say 300 k.p.h. or more? That would be a awesome sight! Thanks for sharing. Cheer's!!!!!!

[@steveapel2961]

@@Sjef0194517greetings, what kind of racebike do you have, and what tracks do you ride? I have 2 ninjas, a ancient ZX 7, and a zx6r. My home track is road America, Elkhart lake. They just held the Indy car race here last weekend, that track is so beautiful with 3 long straights. Thanks for sharing. Cheers!!!!

[@Sjef0194517]

@@steveapel2961 Hi Steve I ride the F1 circuit Zandvoort in the Netherlands and the motoGP TT circuit Assen foremost. Both are extremely fun to ride. And the plan for next year is to ride Spa-Francochamps in Belgium as well. I do this on a old 1999 Suzuki GSXR 600 SRAD. and trying tot get under 2 minutes on both tracks (fastest for a bike is 1:52min)

[@frozenstang3868]

Thanks for another informative video. Learn something new everytime i come here.

[@clementbk9646]

In France both research and motor numbers are displayed in gas stations. I have always wondered what it means, thanks for the explanation !

[@uselessn3ss]

On more advanced systems higher octane will cause the engine to advance timing and actually produce more power .

[@zdx197]

exactly, on high compression ratio engines where you have high timing targets and advance timing you will create more power. That is why when they remap / tune the ECU's other than adding turboboost among many other things, advancing ignition timing is always one of the things they change. More advanced ignition timing = more power. This video is only half-true and doesn't really go in depth with other scenarios.

[@GdeVseSvobodnyeNiki]

The real question nowadays is who GOT the fuel.

[@axelleaxl.5315]

Thaaaanks !! The one I needed to explain to my friends !

[@dukie1616]

Thanks cowboy🤠 Keep up the good work👍👏

[@hectorae86]

Venezuela has better fuel though.... It's only 2 cents per liter

[@sasabarisic8864]

Well, is it really mythbusted? The highest octane rating available in the US is 93 premium which is basically 97.5 RON in Europe. Yet every European country has 100 RON available.

[@RicardoPestana]

i don't know other countries but in Portugal you only have 95 and 98.

[@chillycheeese]

In Germany at Aral gas stations you can get ultimate 102

[@jonadkins9339]

There's plenty of gas stations in the US, at least around me, that sell 100 Octane and even 110. Classified as "Race fuel"

[@zochpeter]

@@chillycheeese haha, yes, full of ethanol and the blend has even less energy content than 95 :D

[@chillycheeese]

@@zochpeter "Full of ethanol" - sure, the mandated 5 percent. However, it has a higher ROZ octane rating and such enables certain engines to produce more power. Also, could you please provide a source for your statement with reduced energy content?

[@davisrs1]

Great video! I can't even count the number of times I've seen people say they use higher octane fuel "because it contains more energy" on a low-compression engine!🕵‍♂

[@masonl.8859]

Nicely explained!

[@DjNikGnashers]

The map on my engine, is designed to work only with 99RON UK fuel. It would be dangerous for me to use any less. And it does make more power on higher RON rating, as proven on a dyno. Decent video, but over simplified to suggest lower octane will give more power, completely wrong and the opposite is true. It's not a waste of money to use higher RON fuel, as proven by 1000's of motorists who get a much better fuel consumption with higher RON, and in fact, save money by paying a little bit higher price for the higher RON fuel, but get more mpg which actually works out cheaper for them overall.

[@TDG2654]

That still means (western) Europe has better fuel than the US. Our standard fuel is euro95, which is equivalent to 91 in the US, which is always marketed as premium fuel. I have never seen the equivalent to US regular gasoline, here.

[@TheCompyshop]

It depends on which state you live in. Where I'm at we have 93 Octane fuel everywhere. But according to his chart, Europe technically has 94 Octane fuel, which in theory is slightly better than what we have here lol

[@craigsowers8456]

Small price to pay for paying $12 a US Gallon vs current inflated price of $5 a US Gallon. BTW, in Russia it's still .50 per liter ... I don't thing the "Boycotts" are working in our favor ... a question for "Davos" participants n'est pas?

[@TheCompyshop]

@@craigsowers8456 Thr Russians also have an average wage of a few hundred dollars a month, so to them that .50 per liter still feels like a large purchase. If they spend let’s say $32 per tank 2-4 times per month, that’s a large chunk of their income just on fuel

[@jungleguybest]

Always enjoy learning from your videos. But here one more thing really pleased me, is your southern accent imitation. I loved it. Thanks a lot. 😊🙏

[@killa8507]

Thank you very much, I will now quality test my tub of cooking oil by getting their octane rating every once in a while.

[@dcskate1022]

Octane has nothing to do with the quality of the fuel. End of video.

[@Ballacha]

"(ron + mon)/2" as octane rating smh. this just goes to show the length america is willing to go to not use standard measurement the rest of the world uses. americans probably think it's edgy but it's actually cringe.

[@429thunderjet2]

I believe you did a good job here. And a lot of good comments here too 👍. I personally use non ox premium in all my small engines, marine and powersports engines and haven't had issues. Ethanol works in vehicles that get used often so the fuel is kept fresh, but can be disastrous for small engines and stuff that is sits for long periods. Because ethanol does degrade fast and also absorbes moisture so it can phase sperate, another bad thing! I have cleaned and repaired a lot of those fuel systems. Also there is less energy in alcohol so it can slightly reduce fuel economy, but the price difference for non ox fuels usually negates that. However I have also seen studies and heard opinions that suggest the use of ethanol has no overall net gain for us all.

[@trewyatt2159]

Man I love your videos.

[@M60E3MG]

I like the old octane testing machine in the video. The “knockmeter” at 7:54 made me chuckle a bit.

[@minkodima]

Thanks a lot, was interesting as always)

[@ahmadpc7]

I love ur work. Keep it up 🤛

[@shaulpreisman5601]

The last 10 seconds… 🤣🤣🤣 Dude, you’re hilarious. Keep it up! ❤️

[@whoami155]

Great video and explanation.

[@qaisibrahim5674]

thank you for the detailed video, can u please make video about gaseous fuels like LPG ?

[@rogercantwell3622]

The UK situation is confusing because the government has created a link between octane rating and ethanol content. 95 RON petrol is E10 now but the 97-100 RON fuels are allowed to stay as E5. As E10 (in theory) has 10% ethanol, it has lower energy content than E5, so in this case the higher octane fuel does contain more energy, but not because of its octane rating. In practice, E10 only legally means "up to 10% ethanol" and some batches turn out to have no ethanol in them at all.

[@MrFranbanietti]

As always, I loved the video.

[@ep5acg]

Your impression of a Texan is scary accurate. Liked the piece at the very end.

[@emotionz3]

Explained absolutely perfectly.

[@motorradmike]

Excellent explanation.

[@jeremytownson1101]

Interesting video. Thanks a lot.

[@noneatza815]

Awesome video as always ! Can you perhaps do one on the difference between standard and premium diesels ? For example if i don't use premium diesel i get a check engine light in my car.

[@jonathansmith7306]

Premium for diesels just refers to engine cleaning additives. Which can help your engine run better

[@michelf9948]

Thank you! Well done again!!!!

[@rudygermain4236]

Thanks for this

[@stevenfarrington2361]

My understanding is that some engines can adjust settings to take advantage of higher octane and produce more power. In 1996 Honda released a 1.6L Civic on the New Zealand 🇳🇿 market which had a budget style fuel injection they called Group Injection. This had only two fuel injectors which I felt at the time was a major step backwards from PGM-FI. However, group injection was also paired with a knock sensing system which Honda claimed could sense and adjust to a different octane rating in every engine cycle - very impressive capability from something that is impossible to achieve in a practical way. In 2000 when 98RON fuel ⛽️ became available in addition to 95RON premium and 91RON regular, Honda NZ claimed a 5% power benefit from 98 in my 1994 Integra VTi-R over 95. I did notice an improvement. Currently I run 100RON in my Mercedes CLK 320 W209 and it goes like a rocket 🚀😀

[@stevescholey3479]

Really good thank you for the perfect Octane explanation on Petrol engines (Gas engines). Do you have the equivalent for Diesel and the Cetane No ?

[@charlescamen5225]

thanks again for a great video. is there any basis for a video on the energy levels for different fuels and or how much energy can be extracted from the different octane ratings.

[@Handlesplus]

I’m so glad that you explained this. I can direct my friends who believe that higher octane fuel has more power than lower octane fuel, to your channel.

[@mkefayati473]

Look, they are all misunderstood. For example, I drive a 2019 VW GTI, and on the gas lid, it says, unleaded fuel only, 87, 89, 91. Now if I pump 87, the car won't have the same HP to the wheel. The GTI supposedly comes with 226 HP to the wheels, so if I pump 87 I'm not getting 226 to the wheels, if I pump 89, I won't get 226 to the wheels. Now if I pump 91, I will get the full performance of the engine. Now I can pump higher octanes passed 91, and that won't add any HP or have any different effect. My engines max output is 226 on 91, so pumping higher octane won't do a dang thing. This goes with every vehicle.

[@MySonse]

Higher octane = more energy (kJ/kg) because of less ethanol

[@michaellorenson2997]

Excellent, thanks

[@ivaylokostadinov1521]

You make excellent content; thank you for that. The topic of fuels is interesting. As I saw from your videos, you are from the Balkans. In this case, you are probably familiar with LPG and CNG conversions. I think this is a good subject for a video, especially with the high fuel prices. The topic is extensive, with many myths about how the LPG will destroy your engine or it is expected to burst your car in flames when you start the engine. But in real life, LPG and CNG are one of the cleanest fuels on the market. Greetings from Bulgaria.

[@guiguitonicmotorsport]

I love yours vidéo. I study a lot with this' thanks a lot

[@boostkash2640]

Very educational .

[@jbstepchild]

awesome video loved the merican interpretation

[@CapeCodCNC]

Been having this argument for 40 years! On older cars it does allow for a timing bump which does give a little bit more.

[@kenc439]

I've noticed that as prices go higher the quality goes lower. I use to get over 500 miles a tank filled up yesterday with a range of 417

[@Roarman57]

Very good video!

[@trevorseals6588]

Great video, a lot of misinformation out there but you nailed it.

[@phillglasson6357]

Regarding compression ratio: is the swept volume into the minimum volume. Using a domed piston decreases the minimum cylinder volume while maintaining the same swept volume, hence a higher CR.