Analyzing Apex Seal WEAR in Mazda Rotary Engines - Years of Testing Different Seals

5 Years of saving used apex seals culminates in this video. Comparing apex seals from stock engines with 100k miles to harder better stronger apex seals from engines that were only ran for 10k miles before a change was made! I am excited to share this data with you, and would love to hear about your experiences with mitigating excess wear inside your Mazda Rotary engine.
Join us on Patreon!
/ radpotential

[@meyerpropertymaintenance4462]

As a business owner and a perfectionist at my own work and attention to detail your information direction with a rotary is impeccable my friend. I have been researching these these rotaries for years just picking a good moment to buy one more then likely an rx8. I enjoy watching your videos because of the detail you put into it. Good stuff dude.

[@Carlos.Rivera]

Same here, he helped me to evade potential lemons

[@btownballer27]

I personally picked up a black on black RX8, it's got a good body 2nd motor and drives amazing only downside, it's a rust belt car that had been passed around like a _____ at a brothel. But she knows how to make love.... to the road. All things aside. They're great. Get one when you can before they get pricey.

[@f3archrist]

​@@Carlos.Riveraget a lemon and fix it, way more satisfying than spending cash on a rx8 that will eventually need a rebuild

[@rebecrra]

I just purchased a 2010 rx8 runs excellent, should I premix ??

[@Finding_Finance]

The materials used in Apex seals make the difference IMO. I think the stock seals and the metallurgy and the R&D put into them make them a superior seal for durability and lifespan for wear compared to any other seal on the market. Premix/OMP won't make as much of a difference as building an engine with stock seals that are designed to be run with the rotor housings and the interaction at the seal interface. I think most aftermarket seals are crap compared to the stock oem seals. I would run a mid-300WHP engine with stock seals and water/meth injection and skip the roll of the dice with other seals. I also think pre-mix is not as effective as the OMP. Mazda spent countless hours researching where to inject oil onto the seals at the key locations in the rotor housings. I would inject 2-cycle oil through the OMP and have been doing so on my FD and FE cars. I also pre-mix about 1oz per gallon in the tank on top of using OMP's on both cars. I have had pretty good luck on both cars with lots of rough miles. The pre-mix selection is highly important. Our cars cruise a lot on the streets and you DO NOT want to run race pre-mix lubricant in this type of condition. There are different JASO standards FB/FC/FD. I choose oils that meet JASO FD standards that have low smoke/carbon/etc. I also choose an oil that can be injected and pre-mixed. The temperature at which the engine runs at is important to choose what oil to run, I choose Motul 710 2T oil. I purchased a bunch off a guy who got paid in Motul 710 for a job and I purchased a butt ton of oil from him to last me many years for a fraction of the price. The 2 cycle oil is designed to be burned in a lot of different engines and burns clean as heck. All of this matters.

[@btownballer27]

What if, hear me out, I beat it like hoo errr everytime I drive it and I don't drive it a lot? I run ams saber pro. One of the best you can buy aside from idimistu. I can't see me sending the revs to the moon often a bad thing for it while premixing.

[@swampyfox8688]

Great content as always! Much appreciated!!! Can’t get enough RAD science! Love it man! Thank you!!

[@BrianGochnauer]

Love your info; but I don't agree with the need for high priced 2-cycle oil. I run Walmart Marine 2-cycle oil (1 oz per gallon, no metering pump) for my 13B NA powered airplane. It burns 10 gallons an hour and it has run hundreds of gallons of fuel and used only Walmart 2-cycle oil. At full throttle and 6k RPM takeoff, it runs about 13.0 +- 0.5 AFR. in cruise probably around 13.4 AFR. The aircraft engine often runs at WOT mostly and so it takes a beating, probably more than most 13B applications; for hours on end. Inspection shows the rotors have ZERO carbon deposits and the plugs are tan to white in color on both plugs. I used 3 piece Mazda seals and there is NO scratches or other damage to the rotor housings. Not a fan of cryogenic treated seals or other 'hard' seals. Compressions are 112-116 on one rotor and 103-115 on the other.

[@DudeItsRobert]

I always enjoy your videos and the amount of effort you put into spreading rotary Knowledge!

[@Sparkling.Fresca]

Interesting deep dive! Not many people get the opportunity to see the varying amounts of wear in different 13b's like you are. Where are you buying that bio premix that isn't an astronomical price? I run Idemitsu and it is a bargain compared to any of the bio premix I can find. As far as my car, 2006 rx8, I premix 1/2oz per gallon and on trackdays I will do 1oz/gallon. Something I have always done since my first rotary (I am on number 4), is I will take out and clean the spark plugs every oil change. Hit them with a carb cleaner and wirebrush them off, and I typically replace them every 3-4 oil changes or if I start seeing degradation of the strap. I also have a mazdaedit tune where we upped the omp oil injection rate, and we actually went for the JDM fuel enrichment map, this is how all RX8s were originally designed in Japan to operate since their emissions were not as stringent as the US's. The extra fuel in the air mixture appears to cool down the internal engine temps, with the possibility of having higher temps building up past the side exit exhaust ports and into the header, which is ultimately not good for the cat, good thing I have a midpipe! Too much internal engine heat in the RX8 is a killer as it will ultimately take out the side seals, which premix is great for protecting these, and also it reduces the temps at or near the spark plugs. Any higher mileage rx8 that makes it past low compression will inevitably blow an internal coolant seal right by the spark plugs if still driven hard at those miles due to how hot that spark plug area gets. The rx8 has some figure like 20% of the fuel is wasted and just thrown out the exhaust which is clearly not good for the stock cat as it will roast itself burning off that unburnt fuel. An additional benefit we have seen to the JDM fuel enrichment map is that the car has a smoother power delivery compared to stock, and the extra fuel also delivers more premix into the engine which has it's obvious benefits. Cheers!

[@vortexau]

I've been away from your content for a bit because I've been busy; but damn this is good! Great deep technical content I live for. Thanks for making this video!

[@jarrad1054]

Thanks for this and your other tech vids. They are fantastic. Got to love the old school plug tuning refence also. Its a must if you run rotors! Two thumbs for you.

[@Bikerpunk330]

Hey RAD thanks for the video and sharing your rotary engine rebuilding knowledge! I have to rebuild my Series 1 2004 MSP Renesis someday so I appreciate your efforts putting these videos together! ✌️

[@NaysayersWillNaysay]

Such a valuable video. No clear bias just straight up facts. True science.

[@scotty305]

This is amazing info, thanks for sharing. I like the idea of listening to the sound the differently-worn seals make, but I also wonder if something like a borescope or cheap USB microscope might be a better way to show the difference. Or if you're able to get in touch with a local university or machine shop to test using a fancy surface roughness meter.

[@gotsauss]

look at the final word at the very end of the video. Live it. Was grinning all the way to class

[@nickw0tup]

Disassembly video bring on a 2 hour special .. Your the man ,love your work .

[@clintonlangerak7972]

My S5 turbo failed with coolant seal groove failure on the front side housing at 142,000kms. It was an unopened factory engine and still made 100psi compression. Was rebuilt in 2012 by a reputable rotary workshop in Melbourne with brand new rotor housings and a brand new front side housing. They recommended and installed RA super seals but with factory apex seal springs. Supposedly the RA seals will warp and not shatter on detonation. They said the RA springs are too hard on the housings. I'd be interested to know what springs were run in the engines you talked about. My engine now has 40,000kms on it, no premix, factory OMP using Penrite HPR40. Recently on the dyno it still makes the same power as when it was rebuilt and run in. I have not had it compression tested because I've had no trouble with it and it hot starts instantly. You got me thinking about the RA seals though. Cheers, great content

[@Rx4Lyfe]

Just yesterday pulled apart my stock FC 13BT to bridgeport secondaries/open up primaries. Discovered apex seals not 2mm factory but 3mm. Apex Slots been machined for 3mm as were the corner seals (not used the FD 3mm corner ones) Must have Spat an Apex on the rear rotor as a chip on the slot on one hence the machining it bigger to remove the burr. No idea how long ago was done, previous owner nor me (20yr owned) had it fixed. Irons minimal markings on the combustion area a light resurface will sort ..no corrosion on water galleries and housings same with minor seal edge wear...but im using new housings. Kinder surprise my builder said 😊 Oh I'm from NZ btw and love your uploads.

[@Unix-cz9km]

Great information, very cool seeing the Renewable Lubricants in action. I am loyal to Idemitsu for Pre-Mix and Oil. Oil and your Fuel also will determine wear and condition of the seals/housings. I found high amounts of varnish, kept fouling plugs, and higher engine temps when using Shell V-Power. I tried others and finally have my holy trinity of fuel: Sinclair, Sunoco, and Gulf. Had much cleaner plugs and power. I personally worked with each oil company to determine what additives and friction modifiers they used, and all were really cool to work with. Shell is known for high amounts of Hydrogen Sulfide 😢Love my Idemitsu and really enjoy buying from rotary shops and giving them full support 🫡

[@Sparkling.Fresca]

Do you have a source on this

[@xMorbidArtx]

@@Sparkling.Frescajust throwing shell under the bus lol

[@LordCakeskull]

I have run Yamaha marine 2 stroke oil for my premix, and in the sohn tank of my Rx8 and its kept it clean and happy for 10 years. I've only run with OEM and atkins seals (non cryo treated) but the only difference i noticed was the longer run-in period with the atkins seals.

[@henryfeliu3468]

Great video, can you share your experience on chatter marks or create a video sharing your thoughts on the matter? I just tore apart my FD engine after a recent rebuild (about 1 thousand miles in) due to low compression. Had some thrust bearing failure, but I was shocked to find some large amounts of chatter marks, 1:1 premix, using 3MM RA super seals. I've read up on the opinions that Chatter marks are a result of a few contributing factors, power lubrication, high heat, and detonation. I'm shocked since I have two oil coolers, premix, upgraded rad as well as vented hood so I'm hitting a brick wall on what could've caused the chatter marks.

[@IamDproductions907]

Rad...My 1988 Gen 2 just blew up on me no less than an hour ago, ran it for about 4 minutes no reving. Heard a few back fires then a tone change in the exhaust followed by a noticeable shake to the vehicle. Did a little research to confirm a blow apex..I came straight here.. if there is a rx7 god to answer my prayers, now is the time to speak🙏🏽🥲

[@paulclarkson2583]

I Wish I could just pull my Rew out and send it over for inspection, its on 122k kilometres at the moment, and still on its Metering pump and twins. Loving the in depth information

[@MassiveDrop]

amazing video my dude.

[@colbyjones1267]

Started running renewable lubricants premix in my rx8 a couple months ago and love it. I use 4 to 6 oz per tank plus the factory omp.

[@boss99gt]

Keep em comming

[@rotaryperfection]

Back in 2005, I rebuilt my 91 Vert with Classic RA seals on used housings that had scorching from blowing the engine. Back then, I just used a drill and round flapper sand disc to resurface the housings. I reused both housings and got the engine to make 90psi (piston tester at 2,700ft above sea level) and it ran for 50k. No pre-mix and only factory OMP. The engine failed again but not because of compression but from the experimental Teflon coolant seals I tried. Ended up selling the car, and the new owner broke down the engine. I had him bring me a housing so I could inspect the wear to see if the harder RA seals had worn away the original scorched damage from previously blowing the engine, and the scorching was still present. I always ran the factory air box and paper air filter because the less dirt inside the combustion chamber, the less wear you get. I'm a firm believer that harder seals need factory OMP because you want the added FILM on the rotor housing from the apex seal scraping by.

[@RADPotential]

This is an interesting thought. I've always been curious how effective premix actually is because it's mixing with the fuel in the air, which is getting combusted. Ideally you have a film of fuel adhering to the surfaces in the engine, but honestly how effective is the atomized fuel/premix actually sticking.

[@rotaryperfection]

@RADPotential 30+years in the rotary game and I've always relied on factory OMP. I just did yearly carbon cleanings to keep the carbon away. Even the non blown portion of my stock FD housing that blew at 108k looks mint.

[@colbyjones1267]

Phenomenal video

[@SaadKidwai]

Thank you.

[@dniksich]

Been watching your videos for a while now and used your videos to help me rebuild my 1st rotary, 1980 rx7 that only has 80k miles on it. Problem is I only had it running once since putting it together and can't get it started again. Getting gas/compression/spark but even w/o pumping the pedal, seems to be flooding out (wet plugs) Was cranking a little slow so I pulled the starter off and took it apart and cleaned it up and polished the armature and it is cranking faster but I still can't get it to start. Only time it did start was after it sat for a couple months with no plugs in it. Any ideas on what I can do to get it started short of push starting it?

[@michaellaframboise7646]

Thank-you

[@mokokawi]

I want to run the sohn and premix in tank ....but i still have catalytic converter....is it ok

[@khullguycr4418]

With oil injection is referring to use the sohn adapter along with the omp? I have about 2 weeks using the sohn adapter on my RX8 how good is to use that mod also i still premix 0.5 oz on the gas tank

[@devultra1125]

I had compression Issues (warm start failures) when I bought my RX-8 (106K Kilometres, don't you dare to use imperial standards). When I first refilled the gasoline and put a lil amount of Idemetsu Premix into the tank aswell, the warm start problems we're gone - till the moment the oil overheated and the whole engine gave up. I definetly can recommend driving it, at least when your engine get's older. For the new engine, I'll go with a clean Oil feed and full synthetic 2 stroke Oil + premix for the first 3000Km.

[@xMorbidArtx]

Premix fixed your hot start issues? Lol

[@devultra1125]

@@xMorbidArtx yeah it did. Within the first tank the engine runned way smoother and started way easier. To be fair, car was third hand and already 106000 Km, so it was just a matter of Times whrn compression issues started to be a problem. A little bit of extra lubtication, and I think a lot of extra compression made the engine operate was better.

[@thatcornfedrx8guy372]

Any opinion on the Lucas Racing Semi Synthetic 2 Stroke Oil in the series 2 rx8 engines? I use it in my mainly stock, only racing beat catless exhaust and upgraded coilpack RX8, and it’s readily available at most auto stores, it’s not the marine type either,

[@haydentaylor4704]

What are your thoughts on the Atkins Rotary apex seals? Looking to get a rebuild kit off those guys for my S1 12a

[@rebecrra]

Have a question on 2010 rx8 no start, was running normal, this morning dropped key, it broke , re assembled key , after that no crank ???? Guessing something with security system ???

[@theiaminu5375]

You should try Klotz ... Probably too expensive for the street , but worth it for racing ....

[@awaddabit2398]

Hi mate, Is it true if you machine the housing you will lose compression and the motor will not start after that Thanks

[@scottrugg7109]

I been running Klotz and just put a Sohn adapter on running good so far!?🤞

[@henrent]

I wonder if having a cross hatch pattern on the inside of the housing would help hold oil there and increase lubrication of the seals like in a piston-style engine.

[@1rotaryfan]

I use blenzall pre mix what you thinks?

[@grumpystony]

That gunk glue coating on rotors aand parts is castor oil like klots but not ran hard enough ,often enough. My builder said it was really hard to clean. And try not to use unless track day.

[@dr_tal]

I have the same premix in my car. I use it with my sohn adapter Also everyone says you have to premix. If the omp is doing it's job you should not have to premix Now stuff around the omp/ engine will break and cause issues with the car and make the omp less effective but Mazda engineering(when Ford leaves it alone) is really good. They even help correct a few hiccups by adding another omp line to each rotor for the rx8 to make up for the fact that because of the new design and shorter seals you could develop hot spots. Those weren't guaranteed but they wanted to add extra insurance.

[@sam49921]

I run the pennzoil marine XLF a gallon is like $22 at wallmart A little more then an ounce a gallon plus omp pinned at 1/4 throttle stock port 12a eats it all up Just went with one number hotter plugs

[@NickDiNunzio]

wow i can’t believe those IR apex seals gouge the housings like that after only 7k miles. is running a harder apex seal necessary for higher boost or power levels beyond stock? what kind of longevity could you expect to get out of a housing with running apex seals that hard?

[@pazsion]

why not use a harder sleeve? or like nitrite the suface or diamond coatings?

[@benbradshaw29]

My last/first engine was running the OMP, but I still premixed at 1/4 oz to a gallon with blue valvoline 2 stroke mix. It died to apex failure, but I can’t really chalk it up to the fuel or lubrication for sure. It had an unknown history, I have a feeling it was either the previous owner's crappy nikki mods, or his port job. It used to have this issue where it would sometimes hit 4k rpms and start struggling and fighting itself, and one day I was highway driving when a seal shattered when I went to accelerate. I never have torn down the engine, but I can see the cracked and chipped seal through the exhaust port.

[@godfreypoon5148]

Check your distributor, that sounds more like ignition timing going crazy.

[@benbradshaw29]

@@godfreypoon5148 you are correct! I later learned it was detonation. Probably the result of having the vacuum advamce hooked up when it was already very advanced. Live and learn I guess.

[@godfreypoon5148]

@@benbradshaw29 Ask me how I know 😓

[@MrRotaryrockets]

I have been using regular and some cryogenic Atkins apex seals for years and I, like Dave believe that the best seal is a soft faced seal for low rotor housing wear ..I would rather replace worn apex seals... then trash housings with overly hard apex seals. I once got a engine that used Rotary Aviation seals.. when one of the oil injector line broke the side of ..apex seals ate the front iron so badly it had to be replaced.. I have built All my engines with Factory apex seals, Atkins seals and a few with E& J seals.. they are all surviving..

[@0PsychosisMedia0]

Don't know much about Roterys but could the type of gasoline cause problems also. Specifically 15% ethanol vs none ethanol gas for at least daily driving.

[@boss99gt]

just got my first rx8 !

[@keithmaiden8585]

Does it still run?

[@boss99gt]

Yes it does

[@nathanoh9121]

what about idemitsu premix?

[@markquickel6499]

Enjoyed the video. Can you comment on why you believe the side seals failed at less than 6k mi?

[@RADPotential]

Detonation. Cracked the corner of the side seal off

[@ADudesRotary]

I sure have got my premix wrong I think I'm at 10 parts per 10000 instead of 10 parts per 1000 (or 1 to 100). I ran my race car for the first time on the weekend inadvertently pushing through 8000 rpm as it was still pulling strong, lucky I didn't detonate the thing i guess. I am interested in your recommended spark plugs for racing, i noticed that you had 2 types, single spark v 4 spark. Which do you think is working best? I was running 102 race fuel as well, did 4 * 30 minute sessions, a real blast. 😊😊😊

[@btownballer27]

I run 100:1 ratio and I have a bottle that has the measurements per L of fuel at 100:1 from what I read thats a good number. More I know I super wasteful but I know I'm very generous with my premix #s

[@rematty69]

That looks like s turbo plug your running in your ute best plugs for a N/A rotary are ngk BR9EG

[@tonymunn]

I blew my '74 RX4's 13B because of a rusty gas tank continuously plugging the fuel filter on a long road trip. When I rebuild it, I will never run it lean again and I will premix with the oil metering pump connected..

[@user-ju6nw1fv5k]

Very cool from British Columbia Canada 😮

[@sublime6896]

may be getting that carbon because the marine oil is tcw-3 not jasoFD like is preferred with rotary

[@KeiichiTheOtaku]

So the real practical question for someone like me, with my 60K mile 2004 RX8 that I've maintained well but without knowing anything that I've learned from your videos for the last several months - does changing how I lubricate my engine really matter? Do I continue to run regular premium gas with the OMP and name brand non-synthetic oil as I always have or do I make changes to my routine or even to the engine (OMP delete, etc.)? Where's the line drawn when the marginal differences in approach actually start to impact engine life?

[@formerdumbkid]

I'm not sure about the RX8 specifically, or if your car specifies, but from what I've seen regular gas is actually BETTER for rotary engines. I believe rob dahm talked about this, but if someone has better information check me if i'm wrong.

[@scottrugg7109]

❤the channel

[@user-yp9gd8cg4k]

as a guy that just starting to go into rotarys do you guy’s have any refference point to buy parts online or what so ever

[@cristhianmiguelaguilarespi2418]

Mazdatrix

[@Silier]

Get your hands on some PAC performance unbreakable seals..... over night parts from Australia hahaha!😁

[@ScottJ175]

Interesting. My 2009 RX-8 came to me with 7,103 miles and wasn't premixed. I immediately started using Idemitsu premix at about a quarter ounce per gallon. My thought process was lightly premix because I cannot disable my OMP. Over the past few hundred miles I noticed my long term fuel trims were getting really high particularly if I miscalculated and premixed closer to a half ounce per gallon. So I decided not to premix for a bit and my LTFT looks a bit better plus I got a jump in MPG. I'm right around 13K miles now.

[@Unix-cz9km]

Did you return to premixing after fuel trims evened out? I have a 2010 RX8 and premix 1oz per gallon Idemitsu.

[@ScottJ175]

@@Unix-cz9km I've not driven it enough to be satisfied with the experiment and I'm enjoying the extra MPG. We had a run of Miata friendly weather so I was driving my NA and after that all my trips out involved either needing to do truck things or I rode with my wife in her Mazda 6. I figure I'll forego premix until my next oil change when it'll be time to do plugs again too.

[@KenBober]

Ill tell you one thing. I will definitely rebuild my next 13b. After the weight and price i just delt with from a "professional" shop...... i really witb i found your channel beforehand.

[@fujiwatertofumi5363]

It’s hard to find a reputable rotary shop these days. It’s either the old owner/workers who really cared about customers and what they do is retired or people who bs things.

[@KenBober]

@@fujiwatertofumi5363 yeah I noticed. When I pulled my engine I wasn't confident to rebuild it. I am now but I have Parkinson's shakes and I'm worried about snapping apex seals. It's ok this will most likely be my last rebuild in the car.

[@Dastardly_X]

🤘🏻 🌟 🤘

[@attackhamste]

can you add liter aswell as gallon... lives in sweden

[@ADudesRotary]

From everything I have read street use 1 to 200, for race 1 to 100. So 10 ml per litre race or 10ml per 2 litres street.

[@pilotohernandez1569]

I'm using klox

[@Caterisma]

I do have a 6 port engine that has only been premixed 200 miles out of 170k if that raises curiosity

[@mingscustoms]

I premix 2.5 oz per gallon on my RA seals, i use redline full synth racing premix in those tall 16 oz bottles

[@TestrunRX7]

2.5! Woah... that is a lot... with no omp I hope

[@mingscustoms]

Yes no omp

[@ultimatejay]

Never want to use synthetic oil a with a rotary- leaved too much carbon deposits

[@benbradshaw29]

I am about to run my first premix only stock port 12A, hoping it lasts a long time.

[@godfreypoon5148]

I think you drew a spurious conclusion. Aftermarket seals are trash. They don't have the development budget behind them like the OEM seals do. I thought this was common knowledge tbh.

[@bobdavis2807]

rob dahm said that 87 in a like 8:1 rotor would make more hp then like 93 do you think he is right

[@knightsportsfc3s]

Who is rob damn?

[@bobdavis2807]

@@knightsportsfc3s Robing these dahm nuts on your face

[@bryarhattabaugh7313]

No experience here rlly fam but I’ll jus suggest half Lucas half of the good stuff for the rotary truck from now on lil carbon won’t hurt😂🤣

[@knightsportsfc3s]

Have you considered water or water/meth injection? I knew a guy who swore by it. He stated that the inside of his engine was spotless.

[@jacobball4594]

A big factor I would imagine is how someone drives as well.

[@rx4mandude]

Why not both ? Just rev it to clear that carbon

[@ultimatejay]

It’s not the premix, it’s those crappy seals.

[@Metancity]

this is true gold on youtube.🤌🙏 thank you