Doctorr

Just finished reading the manual, and NOWHERE does it mention synthetic oil.

Just that the oil must be 5w20, and the quality must be up to the A.P.I.'s latest and greatest standard - "SL".

But no mention, pos or neg, of 'synthetic'.......
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doc

JCC

From all the threads here on oil I get the impression that synthetic is ok due to the ECU controled oil injection. So little is burned that deposits are not a problem. I am not sure of the advantage of syn as the 5w20 SL is tested to very high standards and uses group II base stocks. Some syn oils have a higher detergent additive content for the "not gona change oil and save big $$$" mind set. These detergents form a metalic ash when burned and can foul sparkplugs in susceptible engines. This is the same reasioning to avoid HD diesel oil in high performance gas engines.

BillK

More to the point, currently there is one source that I know of for 5W-20 oil, and that's Mazda's dino oil...

Quick_lude

Castrol, Valvoline, Amsoil and Royal Purple make a 5w20, just off the top of my head..

SA22C

I take the viewpoint that if something isn't mentioned, you shouldn't use it. If Mazda doesn't explicitly state that synthetic is ok, use dino oil. At the end of the day, the Renesis is still desgined to burn oil, and synthetic doesn't burn clean. That point is not in dispute, and until there is a clean burning synthetic, I will continue to use dino oil in all rotary engines that I own. Why take the risk? Even the LeMans winning team used Dino oil. That's good enough for me.

RomanoM

Nothing on the RX-8, but for the TT RX-7 Mobile recommends:

From Mobile:

10W-30
You can use Mobil 1® with SuperSyn™ 10W-30 with confidence.

5W-30
Below 32° F (0° C )
You can use Mobil 1® with SuperSyn™ 5W-30 with confidence.

Take it for what it's worth.

Gord96BRG

But they don't explicitly state to use conventional oil either, do they? What they do explicitly state is to use oil that meets the SL spec. Synthetic oils that meet SL must therefore be just as OK as dino oils that meet SL spec.

Regards,
Gordon

PUR NRG

Meanwhile, Mazda explicitly states attaching the vehicle speed restriction sticker to the steering wheel pad is dangerous. The sticker could interfere with air bag inflation and cause serious injury. Uh huh. :p

You know, Mazda doesn't explicitly state it's okay to drive the RX8 on city streets either.
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Ship Sale

Magnesium

I just happened to be at a Mazda dealership yesterday waiting for my RX8 to be serviced due to the CEL being on.

While I was in the waiting room, the Regional Mazda Rep was doing training in the main lobby area. I overheard him say to NOT use synthetic oils. He said something about designed to break down the oil and synthetic does not break down easy enough.

It may not say it, but Mazda training reps are putting out that word. Take it for what it is worth.

pelucidor

My dealer told me that their rep said NO to synthetic very clearly. It will be part of their delivery speech to every customer getting an RX-8.

r0tor

iTrader: (1)

I will challenge anyone who believes synthetic oil does not burn as clean as dino oil - bottom line is piston engines burn oil too and in order to meet certification standards the oil can't form significant sludge or produce biproducts that will harm the engine, synthetics were made to resist "burnoff" which is not the same as "burning", cars with synthetic oil have lower emissions, and the diesel world is about to go almost completely synthetic in the next 5-10 years due to emission laws - so much for synthetics not burning clean


... oh and lastly, a synthetic oil and an ultrapurified dino oil is the same thing!

MaRX8

It's the "NeverEnding Debate"....

What's this the 10th thred...or so on the subject...

You know what? I like Banana's...........

86rx7

It's a never ending debate with rx7's too. i've heard that mazda was testing different oils back when synthetics were just comming out, and one brand didnt burn well and caused problems, they couldnt single out the brand in the manuel, so they didnt reccomend any synthetic oil. I personally use synthetic in my rx7 every once in awhile (when i can afford it, heh) Racing beat recomends Royal purple synthetic( Racing beat is VERY reputable with the rotary community), and many other tune shops reccomend synthetic for tunned turbo cars. And many, many rx7's have run it without problems. Bottomline: it doesnt really matter, use what makes you feel good about yourself, and your car when you go to bed at night.

jdaled

Hmmm... I got my 8 on 8/11 and I'm pretty sure there was a warning against using synthetic oil in there... but I don't see it in the .pdf users manual I downloaded.

I'll look in a couple mins when I head home from work and see if I can find it. Then I'll edit this post with the info.

Dale

silver8

Service tech's at my dealership said not to use synthetics. Something about not combusting completely (?).

In case there is ever a warranty claim on the engine, it makes sense to use what is recommended. But, if it doesn't say anything in the manual, perhaps you would still be covered.

r0tor

iTrader: (1)

... don't think its going to matter much seeing my dealer will be changing my oil for the next 4 yrs with Mazda paying for it....

RX-8 Zoomster

Oh, so true. :p

Now you're spoiling the fun out of debating these never ending oil arguments : dino vs. synth, 5w-20 vs. other viscosity, oil changes @3000 mi. vs. @7500 mi., etc.

hoorruu

Hi, all! I found this article from marrsrx7.com. (http://www.marrsrx7.com/docs/Oil%20f...%20Engines.doc)
Please read and share your opinion about it.

Oil for Rotary Engines

It is true that MAZDA does not recommend synthetic oil in the crankcase of
Rotaries. I once had a client who used Mobil 1 15w-50 in their 86 Rx7 from
the day he took possession of his new car. His first engine lasted 75,000
miles or so. The replacement one lasted less than 70,000. Both engine
failures were due to apex seal failure. (Broken compression seals) Usually
these engines last 130K +

This was very strange to me as well. Common thinking about synthetics was
that they "lubricated better, could withstand more heat and still remain oil
& suspended
contaminates longer" Other of my clients who had used Mobil 1 in their
reciprocating engined cars found longer engine life.

After a few months of research I found the answer. Rotary engines need 'top
end lubrication' for the compression seals. They are similar to 2
cycle/stroke piston engines in that oil needs to be present in the
combustion process. The internal oil pump has a limited role: It's only
primary jobs are to plane the bearings & to cool the rotors. Cooling the
rotors is done through 2 processes:
1) On the gear side of the rotor the oil comes off the plained bearing
2) On the rear side there are jets in the eccentric shaft that spray a mist
of oil.
OK, no more about Rotors.

The inner oil control ring keeps the oil out of the combustion chamber.
The outer oil control ring keeps the compression out of the oil. This is
very similar to piston engine rings. The rotary system is more efficient in
that almost no oil can get by the control rings.

The Oil Metering Pump injects a deliberate amount of oil into the your
carburetor for the engine to burn. The nature of non-synthetic oils is that
they leave a slippery residue even after a combustion process. This residue
is what hangs around inside your engine to keep the apex seals "WET"
Synthetic oils burn too clean to lubricate the compression seals in a
rotary. Once it ignites, it's gone. Of course you cannot use pre-mix 2 cycle
oil in the fuel as per the rules.

It is known that Zero Weight Mobil 1 will give your Spec 7 more HP
especially on the top end but do you want to sacrifice engine durability? So
many decisions to make.

SA22C

Firstly, synthetic does not burn completely. The theory goes that synthetic leaves ash behind, which will be detrimental to a rotary's health. So goes the theory. Many engine builders, including Racing Beat, recommend synthetic oil in their motors, and they've been building rotaries for decades. I personally don't use synthetic because I don't believe the benefit is worth the cost differential. Many rotorheads do, and they have not seen any detrimental effects.

Second, that document is not official in any way.

Use what Mazda recommends in the RX-8, non-synthetic 5w20. Not because I think that synthetic will harm the motor, but that's what the warranty stipulates.

Gord96BRG

on your Have you ever seen the summary of oil tests comparing a whole bunch of synthetics with conventional oils? The table reports flash point (combustion), pour points (cold), ash residue, etc. All the synthetics left less ash (usually zero) compared to the dino oil. So much for the ash theory. Synthetics are basically much better refined than dino oils - why would the refiners leave in a higher ash content? Simple - they wouldn't, and don't.

So - tell me the page number in the owners manual or warranty book where Mazda recommends non-synthetic anything? MY manual says to use API SL grade oil, and that's it. There is absolutely NO mention of SL non-synthetic or SL synthetic, either recommendations or warnings. API SL period. If a synthetic oil meets API SL, ergo, it can be used with absolutely no warranty problems.

I know dealers are saying not to use synthetic, but I've yet to find anyone that can produce an official Mazda communication (TSB or anything) which advises against synthetics for the RX-8.

Regards,
Gordon

khoney

SA22C - Please point out to me where in the owner's manual it says not to use synthetic. I could find no such recommendation.

hoorruu - Gee, thanks for the warning on how synthetic will ruin my engine. I'm headed out to my garage right now to put dyno in my '87 Turbo II... NOT!!! I've been using synthetic for 160K miles now - guess I must be living on borrowed time

jdl

hear hear! My thoughts exactly.

Elak

One official Mazda source for recommending non-synthetic oil is the tech highlights CD. It briefly mentions that the engine was designed for use with non-synthetic oil.

/Elak

wakeech

just trying to keep things tidier in here... i really wish i had more power, so i could throw these into the "original" dino vs. syn thread, but whatever, this is good enough.

carry on.

Efini 8

personally I am tired of those people saying that Mazda said no to synthetic oil in the manual... where the hell does it say that? stop making up bs people to prove a point. a lot of people take what they find on this forum as the truth and speaking your opinion based on half-assed assumptions is just not right to call the truth and proclaim its integrity.