Hi guys, I was surfing around to learn more about oil, what to put into my 8 when it comes. I know the manual stated to use 5W-20 dino, but I was wondering, where I'm form, in a hot climate, will a higher viscosity oil (eg. 10W-30) be better. Came across this article (http://www.repairfaq.org/filipg/AUTO/F_oil_facts.html), hope it's of any use to you guys.

cheers

Yes, yes,yes!
Use the 10w30 instead. The suggestion of the lower viscosities by the manufacturer has more to do with energy conservation than the needs of your engine. Obviously you can expect slight reductions in horsepower and fuel economy but its probably worth it for those who would like extended engine life.

I also live in a hot climate with an average humidity of 89% 5 months a year. My neighbor told me that he always used straight 30W and told me a long story of how the multi oils break down quicker and cause engine problems. You article says about the same thing.

My only concern is that the Rotary consumes oil. I looked at the chart in the manual regarding temperature and viscosity.

It shows one oil 5W-20 for temperatures -30C - 50C. My area temperature usually NEVER goes even 5C which is rare.

A 10W-20 (no such type) would probably be ideal in keeping with the multi-oil and tempertaure range allowing for warmer zones. If your temperture doesn't go above 50C I don't know if I would go above 20W due to manufacturer recs. IMO.

INfo from Pennzoil website

Penn 10W30 VI 140 Flash 430 Pour -33
Penn 05W20 VI 158 Flash 445 Pour -45
Penn 30W VI 107 Flash 482 Pour -22

compare these with the article information. The higher the better in VI and Flash; lower is better in Pour.

for warmer climates the Flash point seems to be important over 400 is desired. 30W wins. VI is change in viscosity at a given temp. higher is better. Here though I am not certain since a single grade oil would hopefully not be doing too much changing. Pou point is of course how the oil moves when cold. The single grade oil seems to be the right one based on data BUT what about the ROtary and consumption?

Using 10-30 myself. Even though it is easy to find 5-20 it never
gets below 35f degrees here, and many times it is warmer than
105F. I believe I saw a thread showing use of other oil viscosity
oils based on temp from the RX-8 owners manual from Japan.
5-20 oil is classed as a fuel conservation oil.

Mazda changed my oil and tech said use 5-20 and no sythetic
I would be changing oil myself but with the free service I will let them change it for awhile

Did he give u an explanation as to why not to use synthetic?

Originally posted by CruelNewb
Did he give u an explanation as to why not to use synthetic?

Can we NOT DISCUSS about synthetic or dino on this thread, there are many other threads out there, do a search!

Hi RodsterinFL,
those figures are all over, mess-up in my head, anyway, base on your figures, 5W-20 seems still ok for where I am. Temperatures here mainly is around 24C to 35C, extreme case would be 21C-40C (which would be rare). Or would you advise otherwise?

Cheers

to answer your question
the tech said synethic doesn't burn and rotaries need to burn oil

Ask the tech if he personally burned every oil available and can prove that synth doesn't burn! Mazda's ignorance caused death to FDs. They're gonna kill alot of RX8s too!

What needs to be done:
Compare oil pump volume/flow to other RX7s
Compare all engine bearing clearances to other RX7s
Compare idle/running/redline oil PSI to other RX7s

Anyone have the factory service manual?

I am sure that oil PSI, pump flow, and bearing design is what is critical when determining oil viscosity. If oiling specs are similar to the 1st/2nd/3rd gen NA/TII/Twins, then they should be NO problem with picking a viscosity more suited to your weather patterns.

Also, hasn't it been shown that 5w20 isn't the oil choice for certain markets?

You bring up a very critical point with the bearing clearances. If these haven't changed how would 5w20 be suddenly good for these engines?

If you would like to try synethic in YOUR 8 go ahead.
then you can post results for us

That article taught me a lot about oil. But there's a big CAUTION. The comparison chart tells you lots about oil (SG) that you can't buy, and would void your warranty if you could. According to the article, you could research the same numbers for the current SL grade oil. I would also be a little cautious about taking the author's word about how to evaluate the numbers, because current oil may solve some problems that earlier formulations couldn't.
Mitch

That article taught me a lot about oil. But there's a big CAUTION. The comparison chart tells you lots about oil (SG) that you can't buy, and would void your warranty if you could. According to the article, you could research the same numbers for the current SL grade oil. I would also be a little cautious about taking the author's word about how to evaluate the numbers, because current oil may solve some problems that earlier formulations couldn't.
Mitch