Hello all, my name is alex. I have been lurking on the boards for a few weeks reading some posts and now i actually own my very own black rx-8 with sports and appearance. I absolutly love this car although I have noticed poor gas milage like most of you have. While reading some posts i noticed some people sugest using lower grade fuels for better gas milage and some people say that it will damage the engine. I read the owners manual and it even states that using 87-89 octane is fine, you just wont get as much horsepower. So i am confused as to why some people think mazda would sugest something that would be detrimental to the engine.

 

Everyone on here swears by something different, with many people mixing it up on every fill up. Many people say that performance suffers slightly with lower grade gas, but then again, unless your stoplight racing, it really shouldn't matter.

Any grade from 87 to 94 will not hurt your engine.

 

The higher octane fuel does a better job of preventing "pinging".

Pinging = bad.

Pinging + Rotary Motor = Very bad!

 

Also, whenever some performance mods come out it will be more critical to use the higher octane gas (something like CZ Stage 2 or 3).... But as it stands many here swear by the lower octane and use it regularly and without issue (I have not yet read a post that discussed any ill effects), for the record I've been sticking with 91 but wouldn't throw a fit if I dumped 87 in there.