PoLaK

iTrader: (1)

Wondering if anyone could give some merit to this. I heard that when you switch a motor over to Synthetic oil that switching it back to petroleum based oil after doing so would be detrimental to the motor.

Is there any logical explanation to this? Only reason I'm asking is because i change my oil and filter every 2500 and then the dealer does it at 5000.

If it is bad, since i use part-synthetic is that any better?

Also wouldn't adding synthetic to our cars in the first place do the same thing since we can't empty the 3-3.5 quarts of oil inside the coolers anyway?

Rotary Titus

Just bring your own oil to the dealer? Or ask them not to do it and do it yourself? I tell my dealer not to do the oil change now when I take it for service and do it myself with synthetic.
I heard if you switch to synthetic on an old car, it might start leaking oil since the synthetic runs "thinner" and will leak through cracks that the "thicker" conventional oil clogged up. But not sure about switcing back to conventional... probably won't hurt if it's the other way around?

PoLaK

iTrader: (1)

Dealer doesn't like synthetic, he's asked me before "you don't put synthetic in do you"...... "of course not mineral oil is the best thing for a rotary"

RXE16T

This is the first I've heard of this Polak..... but it worries me somewhat.
At 1500kms, I changed to Castrol Formula R synthetic and did so again at 5000kms.

At 10000kms though, I changed back to Mazda Rotary Oil which is mineral based.
I've been running the mineral ever since then, my car's now covered 16000kms.

I could swear my engine now runs better with the mineral than it ever did with the synthetic, but that could just be down to the engine wearing in.

So far I haven't noticed any problems..... but I will be surprised if it does pose an issue further down the line, I hope not.

dragula53

I've heard this issue discussed time and time again.

I asked my dad (who is a pretty serious mechanic) what he thought about switching between dino and synthetic.. he says "So why do they have partially synthetic oils if you can't switch between the two?"

And I couldn't come up with any reasonable argument.

anecdotal evidence, at best, but it made sense to me.

Rotary Titus

hmm.... my dealer never said anything about synthetic, in fact, once I told them to do the oil change but use my own oil which I brought and they said nothing when I handed them 4 litres of royal purple? To be sure they put my oil in instead of usuing their own, I ask them to fill it to the 3.5 litre and give the .5 back for me to do top ups.

RoninJai

I just picked my new 8 up on Friday, and while I was at the dealership, I talked to the service dept. head for 8's. I had just traded in a Mustang that I had run synthetic in since it's first oil change, and had intended to do the same w/ the new car, but the service manager told me specifically do NOT put synthetic in it.

Shamblerock

I thought I also read in the manual about not putting synthetic oil. I am certainly not a mechanic but it seems to me that because the 8 is designed to burn oil and the normal oil probably burns like all other natrual things and end up in carbon deposits. But synthetic probably doesn't burn properly and might leave other types of deposits that accumuate and could plug up something internal. Remember there are very fine jets and passages in our rotary.

bowman

From the US '04 Owner's Manual.

Shamblerock

I checked the manual again and could not find anywhere where they say you can't use synthetic oil so I guess it could be ok.

I know next to nothing about synthetic oil but do they have the same viscosity ratings as regular oil?

Bowman, I couldn't find the manual in a PDF format. Can you post it here or give me a link?

Thanks.

bowman

2004 RX-8 Owner's Manual

1.3L

Just because the manual doesn't specifically forbid synthetics doesn't automatically mean it's acceptable to use it.

1.3L

Shamblerock

Gents, just went to the Mazda Canada site to further check on this issue. In their frequently asked questions section I found this:

QUOTE


Welcome to FAQ's


--------------------------------------------------------------------------------

Can I use synthetic oil in the engine of my Mazda vehicle?


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Mazda has not done any testing related to the use of synthetic oils and therefore does not recommend the use of these products. However, using this type of product does not, in itself, affect the warranty on your Mazda. As Mazda vehicles are not designed with the use of synthetic oil in mind, any negative impact on the vehicle as a result of using synthetic oil will not be covered by warranty.


--------------------------------------------------------------------------------

UNQUOTE

In view of the above, I would refrain from using Synthetic oil.
Since the rotary engine is highly revving engine and heat producer, I am sure if it was 100% safe, they would have said so. How is it possible for them not to experiment with Synthetic oil? Afterall, they do make us pay for the premium gas! If synthetic was certainly better, they would have recommended that as well but they probably just don't want to **** of the synthetic oil companied to be politically correct.

bean438

By that logic then just because the manual doesnt specifically forbid conventional oil doesnt automatically mean its acceptable to use either.

If synthetic was an issue with the car then it would state so in the owners manual.
IPA SL, 5w20, conventional or synthetic, and you are good to go.

bean438

Mazda's comments are confusing.
The warranty booklet says to maintain warranty youo must use fluids specified in the owners manual. It does not say to use fluids specified at the Mazda Canada web site. What if you dont own a pc, or what if you own a pc and dont go to the mazda web site?No where does it say not to use synthetic oil in the owners manual, the "bible" you are to adhere to for warranty purposes.They cannot refuse you warranty for using a fluid that they told you to use.

Shamblerock

Bean, just thought to pass the info. Don't shoot the messanger!

I hear you. It is frustrating and confusing. Oh well, at least they are consistent with all ohter statements they have made in the past!

zevans

I think it's simply that you won't see the benefit.

It doesn't need a wide grade range. (This is traditionally why you might use full synth.)

It's not FI so it doesn't run ridiculously hot for long periods, and there are no turbos to cool. (This is traditionally why you might use full synth.)

You slowly replace the oil between changes anyway because it is designed to require regular top up. Therefore oil life isn't really an issue. (Long life is again a reason why you might choose a synth.)

I don't believe putting synth in will do any harm - but it's not worth the extra money.

Zaku-8

1) IIRC there's a sizable but not huge portion of oil left in the oil coolers during each oil change, so its not a complete swap of oil each time synthetic is switched to mineral and vice versa. There's still a change in predominant type but its of lesser degree than what might be expected.


2)
Mazda has worded this very strangely... using synthetic won't affect the warranty unless there's a problem? So basically Mazda wants someone else to do the research?

MAYHEM

Here are some very good references to the whole oil thing. Alot of reading and very, very informative.

http://www.bobistheoilguy.com/
http://www.batterystuff.com/lubricat...n_tutorial.htm
http://www.micapeak.com/info/oiled.html
http://www.nordicgroup.us/oil.htm
http://www.scuderiaciriani.com/rx7/oil.html
http://www.performanceoiltechnology....ubrication.htm
The last link is a Amsoil site, but is very informative.

Enjoy

P.S. nojooc, it is very possible that you you "might" have lost "power". But with out a befre and after dyno, there is no way of knowing for sure.

Rotary Titus

ah, actually, mazdasport magazine recently ran an article on benefits of usuing synthetic on the renesis. If you want you can search for it but basically even though our renesisi is not FI, the margin of the breakdown point of conventional oil and the inherenet hot spots of a rotary engine is only a 100 or so Ferneheit. And that's with the engine running, not counting when you shut it down. That margin is even more important if you autocross it or drive it hard.

Squidward

I read that natural oils burn easier than synthetic oils. The rotary burns oil by design, therefore using natural oils allows it to follow it's design better?
Not too sure of that.

If it really is true that synthetic oils don't burn so easily, wouldn't it be beneficial to use it, so that you don't lose as much oil as quickly, thereby saving money and time from having to fill up with a quart of oil ever so often?

PoLaK

iTrader: (1)

The issue here isn't whether running synthetic is bad. For the last time Running Synthetic in a Rotary is Fine sometimes BETTER!

The flash points for natural and synthetic oils are nearly the same, so it not burning at all is not the issue.

The main reason people say don't run synthetic in rotary is because the oil seals require a certain amount of friction to seal properly. And Synthetic doesn't have this require coefficient of friction.

IMHO if you ever take your car drag, auto x, or road racing and you not running synthetic your a fool.



I simply want to know if theres any logical reason switching between natural to synthetic in any motor, piston or rotary, is harmful.

MAYHEM

Polack if you don't get a satisfactory answer here, this is a good site to ask the question.