I've been reading around the forums about oil for the last hour and I still can't find a straight answer. So really, what is the best OVERALL type of oil to use for the rx-8?

If it matters, mines an 04 base A/T/

 

when in doubt use what is specified in the manual.

many may argue mazda's highly paid engineers are completely wrong.

I however stick with the 5w20.

 

Yea, thats what I was thinking, but what about the heat factor?

 

5w-30 is recommended by Mazda's highly paid engineers for RX-8s in most of the world. 5w-20 in the US to marginally improve fleet fuel economy and avoid CAFE fines. This thinner oil will also be better protection during cold starts, especially if you're like most Americans and do not warm up your car with gentle driving at first. Might also help the engine run cooler, but many, many people feel it does not provide adequate bearing protection. Thus, some extremely knowledgable Renesis rebuilders here recommend 5w-30 or even 10w-40 for NA engines and perhaps 20w-50 for turbocharged engines or for the track. Synthetic oil is better but Mazda does not recommend it. Long story short, Royal Purple 5w-30 is a great choice as a synthetic. Castrol GTX 5w-30 if you want to run dino.

 

robrect has nailed it - that is all you need to know .

BTW 5w20 and 5w30 will provide identical cold start viscosity .

 

Throw a dart.

 

Alright, thanks guys.

 

Royal purple FTW!