Hi im actually a DSMer but i jus recently purchased a 2004 mazdaspeed rx-8. And i wanted to do the oil change. Now for my DSMs i usually use Mobil 1 racing oil (really thin stuff).....can i use that in the rx-8's rotary? If Mobil 1 will not suffice can someone please recommend a brand and thickness i should use for best performance? Also if you could also lemme know which oil filter brand and stuff is the best for this car.......and just to make sure before the first time i do it....there arent any "special" oil procedures a rotary needs is there? THANKS IN ADVANCE!!!

factory says to use a good quality mineral oil, and just change it on time

I don't risk synth personally, 5w20 is what the filler cap says, but I haven't been able to find any, period. Now I just use 10w30, runs fine. Castrol GTX.

vavoline VR1 race oil 20w50 weight

thanks guys...i really appreciate all the info



as for the 20w50.......that wouldnt b too thick? i want good performance but still perfect streetability

I honeslty don't know anything about the RX8 but i've ran 20w50 in my FDs for the past 2 years with no problems. The heat of the rotary tends to thin the oil faster anyway.

id go with what they recommend for the rx8, they do want a thinner oil in there than they did for the previous cars

They use 0W-20 here in Japan for the 8, only place to get it is from Mazda. I beleve it is a semi-senthetic, so I'd be looking for a durablend in the 5W-20 range, but Castrol 5W-20 should work just fine if you can't find a semi-synthetic.

I am not too happy the local mazda put in 20/50...



I'm thinking more like 10/40 would be a good number.. or 15/40..

I used 20-50 in my FD. It was just fine. And you are right the heat from the rotaries thins out the oil much faster. The important thing is to change it on time.

yeap noticed even after 2 weeks the oil pressure dropped a hair, I change my oil every month usually because its only 15 dollars to change it so ya know

from what i've read on the rx8, mobil 1 synthetic is fine to use, just need to check proper viscosity level, i even saw a short program on using the mobil1 synthetic on the speed channel, but if your not sure then definitely just go with what OEM recommendations

the FD isnt an rx8....the motors arent the same. Main reason why FDs thin out the oil? THEY HAVE TURBOS. the turbos use? OIL. the turbos produce? MASS HEAT. OIL + MASS HEAT = THINNING.



geezus. Anyway, on topic here, I'd run 5w20...all the parts stores here have it in stock so I wouldnt imagine it being that hard too find, but if not 10w30 isnt going to hurt anything.



kevin.

do not use mobil 1 it won;t burn off fast enough and the rx8 also has alot closer tolerances than fd and 20w50 is a lil too thick try to use a 5w20 or 5w30 i personally use royal purple. alot of peopel who work with the renisis reccomend it there are a couple links on rx8club bout it, racing beat also reccomends it i love it i also use 1 bottle of lucas 2stroke with each full tank and it seems to run butter smooth. i use the 1:50 mix for 2.5gal semi synth lucas. but i just use 1 bottle per tank so its like 1:300 or somethin i haven't done conversion

And your science for this would be where?



That is a load. Mobil 1 will burn just as fast as any dyno oil, but it won't leave behind the residue of all the secondary crap that is present in natural oils.

Synthetic is the same molecule that is the target when making dyno-based oil.



Mazda recommends 5-20 because it gets better gas milage. That is all.



I use 5-20 Mobil 1 in the winter and 10-30 in the summer. Anything thicker than that will affect MOP volume, start-up lube and time, oil cooler efficiency and a host of other things I can't think of at the moment.



A good oil filter and regular change intervals is far more important than viscosity, anyway.

There has been a great deal of discussion on this subject at RX8Club. Below is one viewpoint. I have used group II (Havoline 5W20) and group III blend (Motorcraft 5W20). I noticed that the engine ran smoother with the group III blend. I am going to change to Royal Purple 5W20 when my stock of MC is used up.



I also run some oil in the gas as a supplement to the OMP. I use a blend of Fuel Power and Royal Purple 2ST oil. This improves engine smoothness, and gas mileage.





rotarygod at RX8Club:

"Ok here's the official scoop on the oil issue. As I said earlier, I asked the highest people on the planet when it comes to rotaries. First I'll start with Rick Engman's position as he built all of the engine's for Downing. I looked at Rick and just quite simply said, "synthetic oils". His response was, "I wouldn't use anything but synthetic oil in a rotary". Thankyou Mr. Engman! All of Downing's race cars use Valvoline synthetic. He said it doesn't matter if it is a race engine or not. I also told Mr. Engman that many people say you only use synthetics in a rotary because it gets rebult all the time and that it doesn't matter what happens to these engines. I can't post what his opinion are of these people! He did say their engines get 100 RACE hours of use between rebuilds. The Courage is using experimental engine parts that were last used in the 80's and 90's! They care more about the longevity of the engine on a race car than a street car so some people's logic is VERY flawwed.



Now onto Mazda's position on synthetics since I know that the opinion of the smartest rotary person in the U.S. isn't good enough for some people. As I stated earlier, I asked the head of rotary engine development for the past 30 years at Mazda. He designed and built the 787B engine too. In very broken english he told me that not all synthetics are created equal. some are better than others when it comes to mixing with fuel in the oil metering system. The oil metering system is the key. It is NOT with swelling seals. He said that because some oils work very well and others not as well, it is far easier to just officially say not to use them than to say which ones to use and not to. This has actually been speculated for a long time and now we know it's true. I asked which synthetic oils he does not like. the answer is very surprising. The worst synthetic oil for the rotary according to the smartest rotary engine person in the world is Mobil 1. At least Valvoline and Royal Purple are fine. Didn't get any others listed. Rick Engman did say that decades ago there was an issue with some swelling of seals with old synthetic formulations but these have long since been resolved.



To all the people who keep getting on my case and others for using Royal Purple, WE'VE BEEN THE CORRECT ONE'S!!!!!!!!!!!!!!!!!!!! https://www.nopistons.com/forums/pub...#>/biggrin.png



Yes you can switch back and forth between oil's if you absolutely have to."

That's very interesting. I think going to apply that knowledge. I've always have liked synthetics especially Amsoil in piston engines. But I've been using conventional oil in my rotary due to the confusion from the internet. I'm converting back to synthetic.

In the rotary engine, there are two separate lubrication zones, with conflicting requirements.



The primary zone is the rotor interior, stationary gears, and output shaft. The sleeve bearings and gears here need oil with friction modifiers and extreme pressure additives. The rotor interior needs cooling, and has hot spots that can cause the cooling oil to carbonize. High quality synthetic piston engine crankcase oil is a match for these requirements.



The secondary zone is the combustion chamber. This zone is more like the combustion chamber of a 2-stroke piston engine. The rotor seals here need friction modifiers, clean burning characteristics, and solubility in gasoline. High quality 2-stroke synthetic premix or injection oil is a match for these requirements.



Many individuals feel that separate oil supplies for the zones is the best solution. Even if that solution is used, there is a real possibility of additive clash with the two different oils. Some of the 2-stroke oil will work past the seals and mix with the sump oil. Most of us are stuck with the stock single sump. The best oil to use in the single sump is a product that has some of the properties needed for both zones. This compromise is not what mass-market oils are formulated to address. This is also why Mazda elected to formulate special oil for the 787B. Empirical evidence suggests that Royal Purple is a good compromise oil for the two zones of the rotary. It would be very interesting to see scientific tests on Royal Purple and like products in the rotary.