Oh my God, this thread is LONG!!!
Baller - You hit the nail on the head. The reason Mazda don't recommend synthetic oil is BECAUSE THE ENGINE WAS DEVELOPED USING MINERAL OIL.

And the reason there is no disclaimer regarding synthetic oil in the owner's manual is because there is no reason why synthetic should cause any problems, so no reason to ban it.

So you are quite free to use synthetic oil, Mazda just won't gaurantee the results because they haven't tested it themselves. Fair enough. What is wrong with using mineral oil until your warranty runs out, then switching to synthetic?

Oh, and the reference to synthetic type oil above by XEDOS6 is actually a mineral oil that is processed to have the same qualities as synthetic, or the classification index is similar to synthetic, or both (I can't remember). The bottom line is that it is mineral based.

So, go ahead and use synthetic - when your warranty is up. Or when Mazda says it is OK.

 

I found my car was burning oil so I rang the dealership and they said they only ever use Castrol Magnetec oil. Their arguement was that the seals undergo the most wear on start up (they must be geniuses to figure that out by themselves) and as such this oil was best suited to the rotary style engine.

If that's what they say to use, then I guess that is what I will be using.

 

Let me first state that my only real engine experience is in Honda Motorcycle engines for racing. While I understand how a rotary works I am by no means an expert nor do I have hands on experience.

Here's the way I look at this. The real question is not whether or not to use synthetic, its whether or not Mazda will void your warranty if you use a synthetic oil.

As we've all seen, the manual does not say NOT to use the oil. However, the majority of the US dealers are the ones saying not to use it, as well as their service departments. Now, if you have a problem with your engine and you have been using something that they said not to use, but was not documented, you may have to file suit in order to get anything to happen.

Now, which of the following two scenarios do you want to be in:

1) You used good old dino oil (5w-20) and your engine blew up. Mazda says oops and replaces your engine.

2) You used a synthetic oil (5w-20) and your engine blew up. The dealer won't cover on warranty because they said not to use it. You now end up in an argument of opinions and he said she said. Inevitably, you have to file suit to win because its not in the manual. You probably even win, however in your quest to prove them wrong you spent a ton of money on lawyers and court fees and had to wait forever for the courts to hear your case. All the time you are without you 8 and the dealer isn't going to give you a loaner, so you might even be without transportation.

I guess I'm really trying to say that just because your right doesn't mean that it is cost effective to be right nor enjoyeable. Just follow what the dealer says, blame them if things brake, and have fun.

I LOVE this car (RX-8). It is the most comfortable and exilirating vehicle that I have driven. I test drove an M3, Porsche Carrera, 350Z and S2000. None of these cars even came close in the handling department. Now, I'm an ex-sportbike racer so my ideas of handling may be a little different.

Enjoy all, and keep the shiney side up

SuperDave

 

Well said durrada. You and I think alike, I used to be a race technician for Superbikes, so maybe that is why we agree on things.
Here's another twist on this argument:

Have the synthetic oil companies tested their oils on rotary engines? Let them take responsibility for anything happening to your rotary engine while using synthetic oil, not Mazda. If they don't back up their own product, why should we use it?

Food for thought?

 

Before the dealers had the "special" mazda oil available here in Australia, they put a Castrol synthetic 5W-30 oil in anyway.

Cheers,
Hymee.

 

can't let this one pass.

did they also tell you that it was a perfectly normal function of a rotary to burn oil? if not run away from that dealer service dept. run now, run hard and run fast and don't look back. do not go to them again.

 

No, that's not food for thought.

What is the exact wording in the owners manual? It specifies an SFI rating of the oil to be used, as well as viscosity rating.

If the oil you are using -- synthetic or not -- meets those specs and has it them clearly labeled on the bottle, then you are doing what the owners manual recommends.

Case closed.

End of story.

There's no way they can fight that in court. You simply used an oil that was compliant with the spec they printed in their owners manual.

Some vague statement made by a customer service rep will not cut it, particularly since it was not a bulletin that went out to ALL RX-8 owners.

The owners manual should be all you need for ammo.

 

Nope. The oil companies just need to produce their oil to meet certain product specifications - API SL, etc. There are quite a few standardized tests out there, and auto manufacturers have their own specific tests as well - GM and VW/Audi are two that have their own specific oil spec tests.

The oil manufacturers only have to meet the specs required by the auto manufacturers. The auto manufacturers have to define what specs the oil needs to meet. There's no need for oil companies to test in specific engine types. IF the rotaries had any unique oil requirements, then it would be up to Mazda to come up with a new specification test, and require the oil companies to certify that their oil complied before it could be used. That hasn't happened.

Regards,
Gordon

 

You guys just don't get it. Who cares if your right. You've even said it yourself, "Case closed." That's all I'm talking about. The case part. The sheer fact that you have a to start a case because you do something they telll you not to, whether its in the owner's manual or not, should be enough to disuade you from doing it in the first place. Courts suck ! Paying lawyers needlesly sucks !

I'm sure that you may be right about the synthetics, but who cares if you have to go through a legal battle. Not all court cases are started because the other party is ultimately right. They have more money than you, and they can wait for the courts to take their sweet time. Even, when you will ultimately be proven right.

Hey, I'm pretty sure that it doesn't say in the manual not to run the car directly into a wall either, does it ? But, I'm pretty sure that just because the owner's manual talks about bumpers doesn't mean that they will cover your car for not stopping after ramming into a wall.

Once again, I'm sure that you are right about the synthetic, and this is a very interesting thread concerning the science around the oils, I'm just stating what I feel should be obvious to all who try this route.

 

And what about the thousands of 8 owners that never visit this forum?

How will they know?

They won't.

They'll go by the manual. Manual says SFI rating of XYZ. So they'll put in synthetic of that spec.

How will they be wrong?

This is getting awfully philsophical.

 

Sorry, I have to throw in my 2 cents, as well, on this one. I e-mailed Mobil1 a while back and asked for an explanation on this debate: An answer as to whether or not synthetics were not only safe for rotaries, but if they performed superior to dino specifically in the rotary. I didn't save the e-mail (I posted the exact e-mail here a while back), but the response was that it was tested by Mobil and proven safe and superior in rotaries.

For me, the debate surrounds around whether or not the superior properties of synthetic carry over (from piston engines) to this new rotary engine. Mobil says it does. I want to believe it does because of my driving style--lots of stop and go, frequent startups, etc.

 

In fact, it sort of does. It least it pays homage to the aftermath.
Page 26:

 

Forgive me if this has been asked but, this thread is long and I've already read 10 pages and its getting late (1 am).

Anyway heres the questions:

Since synthetics burn at higher temps wouldn't the only problem be reduced CAT life from unburn oil getting to the CAT?

Lets say that synth burns at 1500 degrees and dino burns at 1000. (there is no fact to this just numbers for arguments sake)

Now lets say the motor gets to 1200 degrees and the dino is burning off. This burning off would leave small amounts of "sluge" where the synth would not be burning off so no "sluge". Wouldn't this be better for the motor?

Sluge would be defined as residual deposites left over from the burning process. As many of you know matter never goes away it just changes form, therefore the buring would leave something and the non-burning synth would stay in its original form and still provide lubrication.

Some one please correct me if I'm wrong.

 

I've read quite a few of these synthetic oil threads and a number of other rotary engine sites and have yet to see a claim by anyone where a mechanical failure was attributed to use of synthetic oil. The most credible explanation I've seen is that the issue arose with the previous rotary engine where one particular brand of synthetic oil was causing problems because it left a high amount of residual ash. I read this as nothing more than a poor formulation and not as a property inherent to synthetic oil.

The explanation continued that there would be legal issues for Mazda if prohibiting a single brand of oil and thus the blanket prohibition against synthetic oil.

 

What was the brand that caused problems?

 

If it was an ash issue, I suspect it was Castrol.
Castrol uses the coarsest base stock and has the highest ash content of all the oils.
Bad stuff.

 

All I know everybody who is hating on Synthetics knows a friend that used synthetics and the motor blew up blah blah blah....Please somebody prove all this....please. It really bothers me that so many people are fighting and defaming each other. Just prove it. Please. Just prove it. If you do, you will be doing the whole rotary community a service. Until there is hard proof, I will be using Mobil1 just like I have been in every rotary I've owned. Never any problems.

 

check the flash points of the oils. You can find this on the MSDS sheets provided by the manufaturers..... for arguments sake, some dino might be at 425, and some synth might be at 450... forget what some are, but there's not much of a difference.

I agree with Navilesrx8, prove it! And don't quote older rotary engine failures that you have heard. Prove it on the renesis, as that is the only engine that we are truly discussing here!

 

It is relatively difficult to meet the GF-3 standards for the 5w20 oil grades, so many resort to using 'some' synthetic base stock in their formulas.

The new requirement for 5w20, coming in 2005, is called GF-4, and WILL need synthetics to meet the spec.

Called for or not, soon it will be hard to find a 5w20 that isn't 'synthetic'.......(Motorcraft 5w20 is already listed as 'semi-synth', and is not available as a 'dino'.)

Ford has already registered their 'Motorcraft Full Synthetic 5w20' with the API.
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doc

.....as an aside I claim the first use of Synth (Mobil 1) in a canadian rotary...May 1976, and I had to drive to IDAHO to get some!

 

I don't know how many times I've said this now...

Synthetic oil resists VAPORIZATION better then conventional oil.

Vaporization is not the oil BURNING, its the oil going gaseous on you.

Synthetic oil burns nearly the SAME as conventional oil, actually it BURNS CLEANER so there are less deposits built up from the oil burning.

 

so.... what's the actual benefit IF one does use synthetic? Longer oil change intervals? Smoother running engine?? more power? is it something that the average driver will notice say "wow, this engine's running on synthetic!" if you used it?

 

It's kind of like drinking a good Scotch (blue label $180 bottle) or any just regular Scotch........or in Vegas a $1000 a night hooker or a $100 hooker......both get the job done...but.........

 

I plan on owning my RX8 forever...I swear. I want the best oil to protect against wear. Synthetics offer the best protection. I don't change the oil change interval. I change it at every 2500 miles. If you don't plan on keeping your 8 for long, just use regular dino oil, and change it regularly.

 

FYI -- when you edit a post, you have the option of deleting it altogether...

 

Cool...thanks.