Braden

Royal Purple has performed seal compatibility testing on the components used in Mazda rotary engines with excellent results — including older rotary engine seals dating back to the Cosmo (mid to late 1960′s). Royal Purple’s former Technical Services Manager had owned and raced rotary engine cars using synthetic motor oils since 1985 with excellent results. Extensive research by the Royal Purple Technical Services department has been unable to determine a credible and valid technical explanation for this recommendation against the use of synthetic engine oils in Mazda rotary engines. Please note that review of vehicle owner’s manuals for the Mazda RX8 shows no warning or note about not using synthetic engine oils. In the early development of synthetic engine oils decades ago, there were purportedly some seal compatibility issues. Today’s synthetic oils do not have the compatibility issues of the old oils. There is no substantiated evidence of seal compatibility issues with Royal Purple.



Here are some facts:

The Mazda Factory racing departments recommend and use ‘synthetic’ oils including the winning 1991 Leman’s 20-G 4 rotor Mazda 787B.
The MazdaComp USA printed manual (now Mazdaspeed) recommends the use of synthetic oils for racing conditions.
Royal Purple Motor Oils have been used in rotary engines (both race and street) for 10+ years with excellent results.
Royal Purple Motor Oil is compatible with the bearing material, sealing elastomers and combustion seals used in a rotary engine.

Here is the response I then received from Valvoline on the same question I submitted to them.
Braden, thank you for contacting Valvoline Product Support with your questions about the use of Synthetic oils in a rotary engine.

The major reason Mazda does not recommend the use of Synthetic oils in their rotary engines is due to this style of engine being prone to burning/consuming oil faster than traditional combustion engines however, you may use Synthetic oil in your rotary engine.

Synthetic oils will not cause any damage to a rotary engine, we just want customers to know that they may burn/consume more oil than they normally would if they were using conventional oils.

If you have any further questions, please feel free to contact us via phone at 800 TEAM VAL or by email at valsupport@ashland.com for assistance.

Thank you and have a great day.
Dave

Now this is the info from Black Halo Racing Rotary Shop
The Great Oil Debate:

Trying to figure out which oil is the best to use in your Rotary is just as impossible as it would be for a piston motor. There are dozens of oil manufactures of which many of them provide their products for various race cars and suggest theirs is the best. Nearly every person has had a good or bad experience with every oil brand on the market. It’s up to you to decide which oil brand to use that fits your needs and budget.

Black Halo Racing’s recommendations on oil are very simple. Stick to a couple rules when choosing your oil. First, ensure its quality synthetic oil and secondly ensure that you use a 5w-30 SAE rating or higher depending on your climate.

Black Halo Racing recognizes that the Mazda manual calls for a 5w-20, non-synthetic, oil to be used in the RX8. Our research and testing as well as various engine rebuilds have shown these suggestions to not be enough to protect your rotary engine. So how is it we know what’s best for your car when Mazda has engineers with PHD’s and millions of dollars at their finger tips?

The reason is Black Halo Racing is not restricted by political or environmental regulations when making suggestions for your vehicle. Mazda, like any other automotive manufacturer, must create a vehicle with operates in all conditions, climates, and also falls within government regulations. The decision to use 5w-20 is mainly environmental and fuel mileage driven. Thinner oils require the motor to work less hard during its operational process. The trade off is less protection of metal parts.

Mazda’s decision to not suggest synthetic oil is due to the inability of them to test fully synthetic oil within the RENESIS motor. Unlike conventional oil, no two synthetic oils are created alike. There are various differences between synthetic oils and Mazda cannot fully endorse one brand over another. Finally, there is no data to show what the long term effects of injecting synthetic oil via the Oil Meter Pump would be. It was easier for Mazda to suggest not using synthetic oil in the end.

On top of this, look at atkins racing, racing beat, Mazda Racing etc. ALL USE SYNTHETICS IN ROTARY ENGINES!

In my opinion, after days of research I have put into this. Synthetics are better than conventional oils for the rotary engine as well. P.S. Mazda MAKES AND RECOMMENDS synthetics in europe and Japan. I've gone to synthetics. It's better protection. As to WHY Mazda would then say to use conventionals if it's actually worse is explained above.

Carbon8

iTrader: (4)

RP UOA disagree with you.

skc

I have been using full synthetic oil on my car since the supercharger went on. The car had done 98 0000km at the time on the original engine.

Over the last 3 plus years I have done another 33 000km without any issues. I have developed an oil leak at the eshaft however, it is more to do with the age of the car and the hard life it has endured.

If I rebuild in the future I will end up with a SOHN adapter to inject 2 stroke oil. For now I am premixing with some cheap Penrite 2 stroke oil.

mbirt

Why not just run Rotella T6 5w-40 synthetic?

9krpmrx8

iTrader: (46)

I have ran several weights and brands of oil over the years and have had an oil temp gauge for years and there has been no effect on starting oil pressure or length to full operating temps throughout the use of these different oils. I am sure Dan and others in the Northern Canada may during the winter (not that Dan drives his then though, lol) but I doubt anyone below the Mason Dixon line has to concern themselves with it.

Now having a true bypass oil thermostat, -10 lines, and different coolers has had an effect though. Personally I just let it warm up for ten minutes before I go out and beat on it.

gwilliams6

Originally Posted by Spirograph View Post
I like the Rotella for the extra detergents, but I'm always wary about not pushing the RPMs high until the oil is at operating temp. which I try to set at 10 minutes of driving since I don't have a guage installed. What I'm hoping is that the Mobil Euro will provide extra protection at cold. Can anyone tell me how much quicker Mobil 1 0w40 gets up to safe operating temp for high rpms vs. Rotella 15w40?


Spirograph, I am not here to suggest what oil you should use synthetic vs non synthetic, feel free to use what you like. but just would like to pass on the fact that high detergent oils and gas, while maybe helping with carbon buildup, ALSO tend to strip away the lubricating thin layer of oil on your seals and inner rotor housing. So you are helping and hurting your engine using high detergents. This is assuming you are still using the oil metering into your engine. That is why I never used high detergent in any of my seven rotary car engines for street or track. Back in my track days, I did use Amsoil full synthetic in my race rotaries with great success and longevity (never a single rotary engine failure, ever).

tbiggybig

I need someones input im honestly not sure what oil to put in my rx8 because im not sure what oil was already used in my rx8 i heard somewhere you can go conventional to synth but not synth to conventional so what should i do hope that the guy before me used conventional or just try and used synth i also heard that its safe to use synth/conventional mix in this case but idk what effects that has on the rx8 (being dead serious new rotary owner)

nycgps

iTrader: (1)

is it ur car, or its someone else's car ?

use whatever YOU want.

For the record, I use FULL SYNTHETIC and FULL SYNTHETIC ONLY

Sphere

Just switch to synth and premix gas with Idemitsu unless you have a sohn. Mixing synth and mineral isn't as bad as you may think. I would suggest just changing to synth though, and keep a very serious eye on oil levels and always keep her topped off.

I'm personally running RP HPS 10w40 atm with Idemitsu premix on every fill up. I may switch to something else, but I'm giving the RP HPS a thorough checking out. If you do try RP, I would suggest the HPS and not the regular RP. The HPS has a better blend and additive package.

gwilliams6

I used Amsoil pure synthetic in my racing RXs over the years, but i use dino oil in my current street RX8 ONLY because my 2008 is still under the engine warranty and some Mazda dealers have denied rotary engine replacements to American cars that ran synthetic oil, even though it is widely used and recommended elsewhere in the world. Once my warranty is finished I will switch to synthetic. And I premix in all my rotary cars I have owned. So just be careful with your oil choice if you are still under the 8yr, 100,000mile engine warranty. but if you are not, certainly use the synthetic.

rotarygod

It's your mistake if you tell a dealership that you use synthetic. Always play the ignorance card.

gwilliams6

SPHERE, FYI the rate at which oil is injected into your RX8 depends mainly on the load you put on the motor, not simply the miles. I could drive 10,000 miles at 2000rpm and not inject as much oil as someone driving the car HARD at 7000+ rpm for a thousand miles. But i would be making much more carbon at 2000rpm. I have owned seven rotaries.

There has been just as much evidence that synthetics don't harm the newer apex seals as there is that synthetics don't combust fully in the short ignition cycle. The key factor is that Europe and Asian market Renesis engines run fine with synthetic oil. It is solely the owners choice once there are no more warranty issues, but not the wisest move to let your dealer know in America that you ran synthetic oil when you need a Mazda approval for a reman engine. They can and have denied it solely on that basis.

Legally, my 2008 manual and owner's dvd that came with the car both state in very clear language DO NOT USE synthetic oil. That is all Mazda needs to deny warranty coverage on my year RX8.

TeamRX8

iTrader: (25)

This thread is the ignorance card ....

tbiggybig

I wouldnt think there would be a problem converting to synthetic warrenty wise because im pretty sure its expired i have a 04 rx8 6speed mt with 85k on it im the 6th owner i believe my main concern is that i dont know what oil the last owners used and im pretty sure theres no way i can find out without getting viscosity tests (correct me if im wrong) which i have no idea of how to even go about that. so they could have used conventional or synth or vegitable oil for all i know... i was wondering what the safest way to go about it without damaging the engine because i heard if you try going back from synth it can cause problems (if they even used synth) i was thinking just go straight to synth unkowning of how the oil was maintained in the past so pretty much would 85k be a bad time to just hop straight to synth oil or should i risk running conventional and hope thats what they maintained it with the car has been seviced by the mazda dealer the first 45k (carfax service history says so thats as accurate as i can get but feel somewhat safe to assume they used conv) but the rest was by other companys dont know what they used so is it safe to go straight to synth with 85k?

Sphere

Not sure where this response is coming from. I never once, nor would I ever, recommend someone say anything to their dealership that may void their warrantee. I also never brought up the rate at which oil is injected, don't know where that's coming from, but as a rotary owner, you also know better then to drive 10,000 miles at 2,000 rpm....I hope.

Sphere

Synthetic and mineral oils mix fine. You can switch between the two without any problems. However, the general consensus is that if you have run mineral oil in a vehicle which now has high (over 100k) miles, it's unwise to switch to a synthetic (of the same weight) as synthetics can be somewhat thinner to an equal weight mineral oil. But you really shouldn't be to concerned with mixing synthetic and mineral oils for the most part. I'm sure you'd be ok with synth, I would keep it a little on the thicker side though, 10w40. 5w20 is just to thin for this engine, and 5w20 synth would be slightly thinner.

Weights and synth vs mineral is a never ending debate, so in the end...you have to make your own decision.

gwilliams6

absolutely no problem with mixing synthetic and dino oil . Your car will be fine and then in 3000 miles you will drain out half of it anyway and fill with the oil and weight of your choosing. in your case with a 2004 there are no more warranty issues, so switch to full synthetic then. This oil debate is endless and never will there be a complete consensus, so don't worry, be happy !

tbiggybig

Thank you most helpfull post of the day.

androbot2084

Mazda of Japan issues a caution concerning the genuine Mazda SyntheRenesis oil and Mazda of America translates this from japanese to english as a command not to use synthetics period or else no warranty.

Using this logic I suppose driving the car will void the warranty because I could get killed in an accident.

Nadrealista

Do you have copy/link to this statement?

Jboogy

I'm not sure if anyone has seen this but it's a very interesting read....
Thought this was probably the best place to post:

http://www.rotaryeng.net/rotary-oil.pdf

9krpmrx8

iTrader: (46)

That is old as hell and not relevant at all for our use.

Jboogy

It is exceedingly old but I do not understand how it is irrelevant. I've read a significant amount of your posts and it shows that you have a lot of experience - would you mind expounding upon your assertion?

Loki

iTrader: (1)

Thanks for sharing. Jives with my current understanding of the subject.
It's all in the base stock / oil group. Some synthetic oil is going to be worse than others because the base stock is wrong. I don't know about what commercially available oil is polybutene-based, but POA or ester based oils seem safer in terms of internal varnish and apex seal deposits. Provided they're changed often enough. Polybutene sounds kind of weird as a base stock, but I'm not a lubricant engineer.

9krpmrx8

iTrader: (46)

These tests were on an older carbuerated on rotor engine and not a Renesis. The samples used can't really be compared to modern oil formulations. And "spit back" likely doesn't occur on a Renesis due to the changes in the Apex seal design.


But I do think running the SOHN adapter with a good JASO FC 2 stroke oil and premixing that same oil in the fuel while running a good full synthetic engine oil in the crankcase is the way to go.