Minimum HTHS for Rotary engine in RX8?

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3 weeks ago I bought 04 Mazda RX-8. It will serve dual duty as a daily driver and occasional track car.

What is the minimum HTHS viscosity for good wear protection in the rotary engine? I know you want min HTHS of 2.9 in piston engines. How does this plays out in rotary engines? Has there been any studies that examined this?

Please keep in mind that I do track this car so it will see sustained(25-30 min track sessions) high rpms in the 6000-9000 range. It does have dual oil coolers so I doubt oil temps will get over 250F.

I am thinking of running redline 5w-30 as per Dave recommendation.
 
I would use anything that is not rated as "Energy Conserving" or what ever it's called now. Redline 5w-30 with an HTHS is 3.8 and NOACK of 6 looks like a good oil
 
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You don't need a min. HTHS of 2.9 in ALL piston engines. It depends on the design and the type of service.

I haven't come across anything discussing HTHS viscosity in rotary applications. I'm interested to see if anyone comes up with anything.
 
I would recommend you join a mazda RX-8-specific site for good/better info. Good luck, looks like a fun car. Was the engine refurbished by mazda once already - I hope? These engines are designed to inject/BURN CC oil - so they may want a low ash product or ?? Given that info, i would NOT suggest running Mobil 1 EP or a CI Diesel product. BuT who knows?
 
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With how often you should change oil in these things, it doesn't really make sense to use a high priced synthetic oil. But, if you have money to burn, go for it.
 
Any current oil spec will work fine.

It extremely important to do frequent oil changes. Never go over 3k/3mo and it'll last a long time.
Also, its critical to top off oil at EVERY fuel fill up.

Make sure you have all recalls/TSBs addressed.

Run a little 2-stroke or UCL premix in the fuel always since 'emissions tuning' doesn't inject enough motor oil for seal lubrication.

Research oiling improvements in the form of aftermarket coolers, thermal-pellet mod, upgraded oil pump, increased oil PSI, aftermarket oil pan, windage/aeration control, and the 2-stroke oil metering pump adapter.

With the movement toward some low/mid SAPS oils, I'd probably go to Synpower MST/HST or the Mobil1 ESP oils, or equivalent. Anything to reduce crud buildup, will help a neglected engine.

Run a bottle of quality FI cleaner at every OCI. Gumout Regane, Techron Concentration, 3m, BG44k, Amsoil PI, Redline SI1, FP60, Neutra... are some that I'll recommend.

Get a quality oil temp gauge since your oil temp should NEVER go over 200F. Rotary engine oil is 'cold' compared to 'piston' engines.

Never shut off a cold engine(no swapping parking spots without a 10 minute ride). If you must, rev to 4k just before shutting her off. The flywheel momentum will help 'vent' the engine to prevent flooding restart issues.

Research your VIN at the dealer. You probably already have a new engine or 2, since most rotary owners were/are clueless.
 
Originally Posted By: CharlieJ
With how often you should change oil in these things, it doesn't really make sense to use a high priced synthetic oil. But, if you have money to burn, go for it.

There's a LOT more to synthetics than being able to change them less often.
 
car has 56k miles and had engine changed at 20K miles, so engine has 36K miles on it.

when I first got it I changed oil with shell rotella 5w-40. I have ran one track weekend with that. It used about 1 quart in 6 30 min sessions on the track, but it does that by design since it injects the oil into combustion chamber. So low ash clean burning oil would be best I think, hence redline.

I am going to VIR next monday/tuesday and will use the redline oil I have from my Audi stash. I also took sample last friday and hopefully will get results before VIR.

The only piece of information I am missing is what is the minimum HTHS to minimize wear..I guess I can't go wrong with redline....

I also got whole case of idemitsu racing premix oil specifically designed for the rotary.
 
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Idemitsu racing premix is specifically designed for MARKETING. Don't be fooled by the label. Use ANY current spec 2-stroke oil for supplemental premix.

HTHS isn't something to worry about. Your temps are pretty cool and viscosity can be adapted as needed. 5w40 is an excellent choice. Fuel dilution will soak the oil quickly which is why I recommended the frequent oil changes. Synthetics add to unneeded cost with frequent oil changes.

You can't go wrong with Redline in almost ANY weight.
 
Originally Posted By: unDummy
Any current oil spec will work fine.

It extremely important to do frequent oil changes. Never go over 3k/3mo and it'll last a long time.
Also, its critical to top off oil at EVERY fuel fill up.

Make sure you have all recalls/TSBs addressed.

Run a little 2-stroke or UCL premix in the fuel always since 'emissions tuning' doesn't inject enough motor oil for seal lubrication.

Research oiling improvements in the form of aftermarket coolers, thermal-pellet mod, upgraded oil pump, increased oil PSI, aftermarket oil pan, windage/aeration control, and the 2-stroke oil metering pump adapter.

With the movement toward some low/mid SAPS oils, I'd probably go to Synpower MST/HST or the Mobil1 ESP oils, or equivalent. Anything to reduce crud buildup, will help a neglected engine.

Run a bottle of quality FI cleaner at every OCI. Gumout Regane, Techron Concentration, 3m, BG44k, Amsoil PI, Redline SI1, FP60, Neutra... are some that I'll recommend.

Get a quality oil temp gauge since your oil temp should NEVER go over 200F. Rotary engine oil is 'cold' compared to 'piston' engines.

Never shut off a cold engine(no swapping parking spots without a 10 minute ride). If you must, rev to 4k just before shutting her off. The flywheel momentum will help 'vent' the engine to prevent flooding restart issues.

Research your VIN at the dealer. You probably already have a new engine or 2, since most rotary owners were/are clueless.


+1 on everything!!!

Sorry to say it. But I dumped my Rx8 AS SOON AS I COULD once I was out of the red in my autoloan.

The things are fun to drive in the twisties, but are BAD as daily drivers.

They are not that fast. They get bad MPG. Lot's of issues with engines. Man, I don't miss that thing. I was getting better MPG in my 6.8L V10 F250 than the Rx8.

Change the oil every 3000k. When you change the oil, a lot of the old oil stays in the oil coolers and lines. So a oil change only gets you some new oil.

Did I say that I DO not miss that car!!!!

lol
 
Mazda is pretty lax for the RX-8. From what I've seen, it's just API SL or better, 5w20, non-synthetic.
 
Originally Posted By: Johnny
I thought Mazda recommends to not use synthetic oils in the rotary engines. Something to do with the apex seals.


I've read that many times too. Never owned one, so I never really researched the truth (or lack thereof?) behind it. Probably just as hot a topic on the RX forums as, oh, "how much ZDDP do I need for flat tappets" is here ;-)
 
Just a general question.
If Grp III is highly refined mineral oil, would it work in a Wankel?
FWIR, syns are to be avoided in Mazda Wankels because they don't burn cleanly, and may cause an acumulation of deposits around the exhaust ports, which may in turn damage the tip seals.
Is this a problem with Grp IIIs?
Mazda does offer their own brand of oil that is labeled as synthetic.
Is it Grp III?
 
Originally Posted By: dparm
Caterham, you can't run synthetic or even semi-syn.

Care to elaborate?

Since Idemitsu has a line of 100% synthetic rotary engine products the OP may want to contact Idemitsu or one of their dealers for a recommendation.
 
Originally Posted By: mechtech2
Before emissions, those rotaries could SCREAM

:) nothing a midpipe can't fix..they are so smooth you don't even know you are hitting 9000 redline until you hear beep warning you to shift :)

I just changed ignition coils, cleaned MAF sensor, cleaned TB and put in new front brake pads(EBC yellowstuff for VIR)..car is even smoother now..it really is a blast to drive..

my other car has twice the power but is not as fun and agile.
 
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Originally Posted By: CATERHAM
Originally Posted By: dparm
Caterham, you can't run synthetic or even semi-syn.

Care to elaborate?

Since Idemitsu has a line of 100% synthetic rotary engine products the OP may want to contact Idemitsu or one of their dealers for a recommendation.


I guess I am confused too, then. Mazda explicitly says do not run synthetic or semi-synthetic. Now we're getting into the old "what is a synthetic" discussion.

Just repeating what my old roommate's owner's manual says...
 
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