Like several knowledgeable people have said Mazda recommends 87 octane. unless you are boosting more than stock you will have reduced engine performance on higher octane fuel! You can run a higher octane rating fuel if you are worried your engine has carbon buildup, thus having hot spots, creating detonation.

Mazda designed the car to run on 87. But I guess all you kids who have been here for a month are smarter than Mazda right?

:rolleyes:

:icon_tdow Most of you obviously live in the US. You fill up with premium instead of 87 over here and its a good $10-15 more every tank without fail!

hold on now buddy, I have been around rx7 for a long time, and i know what adversed affects of a T2 that was ran on regular BONE STOCK for the course of its 62000 miles of life was. its called detonation. before you smart off and get an attitude, take you engine apart and look at it. maybe the car was designed to run on 87, i have a tech sheet that speakes diffrent. you tell me, mazda of yester years or todays mazda. alot has changed and to call someone a liar that you dont even know, that thats balls buddie. this is exactlly why it took me so long to to join this fourum is because i know theres allways arguments. Its rather funny how some people can that a discussion and turn it into a pissing contest. Im done

I'm sorry, you're right. Mazda had sooooo much more to gain by saying the car would run on regular rather than premium. Maybe you should post your tech sheet instead of just claiming you have one. Also while you're at it would you please explain to the rest of the people running on regular how their engine defies the laws of physics. Thousands of people have run on regular and their engines lasted 125k+.

91 or better
 

I only run 91 in my car with a little two stoke oil

I only run c-116 in my na, everyone tells me it's overkill but I figure I should do it for the detention resistance right?

:rolleyes:

???
 

how much better does it run with that

Wow.

:lol::lol::lol::lol::lol::lol::lol::lol::lol::lol:

This thread made me LOL!!

*ahem*

Let's start from the beginning my young n00blets:

I assume that you all know what octane is and what the rating is for. If not, please utilize that fine search option at the top right hand of your screen, or simply use google.

A rotary engine prefers a quicker burning fuel. NA engines will actually run better and possibly achieve better mileage with 87 octane. A stock TII owner's manual IIRC, says to utilize 87 octane. HOWEVER: Know that most of these cars are modified and as such, fuel amount and octane should be adjusted accordingly. Lastly, if you don't know what you are talking about, please refrain from spreading ill-informed opinions, conjecture, and hear-say. This is a new member section and people come here to learn facts. Not "my friend" or "I heard", just facts.

Yes, it is fine to run on 87 if it's a stock S4. 91 or 93 is recommended on S5's. Enough of this.

Same here I read the owners manual


ive been using premium doesn't seem to like it, I have s4 I'm about to revert to 87 or 89 which ever I find lowest on the pump


ill message back with the results

If the engine is not running well on premium fuel, then there is either something wrong with the engine or with the fuel. If it is the engine, then lower octane fuel may make the problem worse and even cause major damage. What exactly do you mean by "doesn't seem to like it"?

OK, just find another 8 year old thread and attach your results to it. ;)

If you have hints of detonation then go for the premium, if not then 87 it is.
Just be carefull, d3tonation is not always easy to hear-spot.

I would agree that 87 with no detonation would be just fine.

All turbo engines require premium fuel 91 or higher to run to there optimum performance
as well as using full synthetic oil

Its amazing how these myths continue even in the age of the internet where it is easy to find the correct information. :facepalm: