They have had several knowledgeable member run test between 87 and 93 that showed no performance difference. Again it is your money and if it makes you sleep better at night knock yourself out but the tests show no difference and one guy showed a performance increase with the lower octane. Do a search and you can read it for yourself.

As a side note, many rotary race engines will run on octane as low as 80 oct because the rotaries design lends it self to better performance with low octane fuel. This is because of the long narrow shape of the combustion chamber.

 

pull the room fuse and try again..

beers

 

Yep, I have run 87 octane since the first day and never had any detonation. If you are running nitrous, FI, or the RB re-flash then surely upgrade your octane. Otherwise, why give the oil companies more money....

 

Humm me i put about 140 $ each week

 

blehhh, i just tried midgrade and almost seen like i have less power?...

 

Isnt that *pull the battery* better than *pull the room fuse* ?

but my Rotary just hate the cheap stuff, at least during summer months.

Your butt dyno failed !

I tried 89 and 93, feels the same to me.

 

i use midgrade all the time. no difference with 91 or 93

 

damn, i guess my butt dyno sucks =(

 

I am usingo premium. Thinking in using aditive for impruve the optanage.

 

drunk rx8 posting? thats a rare one.

all octanes have additives. its required by law. that makes no difference.


and seriously guys, it amounts to what.. 4 bucks a tank? maybe $25 a month? there is no way i paid $20,000 (21 otd) for this car, and $4600/year in insurance to skimp on $25 a month. $300 a year is a small price compared to other expenses this car accrues.

 

^throwing away your money.
And I'd get different insurance. That is crazy. I pay $600 a year.

 

There were some times that I had to use regular unleaded. I lost mileage so it did not save money anyway. Besides, even if the mileage was the same, I am too paranoid to run anything other than Premium.

 

Dude! How many speeding tickets do you have. I pay 1/4 what you do for my 8, an SUV, a motorcycle, and two houses all put together. I'd call around.

 

Sunoco ultra 94 FTW

 

fuse works.

beers

 

Show me where! Its all been butt dyno's.

Not one true dyno test using Octane.

Our cars run so hot and lean on the top end that using regular is abuse.

If you never go to 7500 RPM you may be ok. But I would not bet on it.

 

I usually run the cheapo in mine and runs fine, every now and then maybe once or twice a month ill put premium, but about to slap on a turbo in the coming weeks so for now on its premium.

 

i was talking to my friend who has a GTI, and he was saying that for his GTI he knows if he puts in 87/89, the car will "Detune" itself and loose horsepower, maybe the "lost in power" i felt was the car readjusting to the lower octane for our car?

 

He's running a turbo, Octane has a far greater effect here.

 

You are correct in that a lot of people use the Butt dyno which is as worthless a gauge as you can find. There were however at least 2 posts I read on this site through the years that used a dyno to test the oct. One reported no difference and the other showed an increase with the lower octane.

Also I run my car regularly to 9000rpm in the dead of summer with out a single issue, all on 87. Lets also not forget that Mazda states that you can run 87 in the RX-8, at least for the 05 model year and I don't know of anything that has really changed with the engine through 07.

I would also agree that our cars run hot but I don't think they run that lean at higher rpm. It is pretty common knowledge at this point that Mazda richend the mixture to extend CAT life before the car was released. So I think it is save to say the car is not all that lean in the higher RPM range. I also believe I read Mazda Maniac reporting that the new flash is a little leaner at higher RPMs but I would have to double check this.

Cheers.

You are correct

 

I wonder if some RX-8's handle lower octane better than others, too. Mine seems to be fine no matter what I put in it.

 

I due think this is true, there are those out there that can not run low octane with out knock. This could be a function of many things from very good compression to carbon buildup. I do believe most will run just fine on 87.

 

Can ANYONE here tell me WHY I should use premium other than your butt dyno or your brother's uncle told you to or your friends xyz car does better with it?

I have driven rotaries for more than 15 years, RX-3's, and 7's in both 1st gen and 2nd gen guise. There are 2 race-prepped 7's in my garage (SCCA road racing) and a new to me, used RX-8 in my carport. I have always used 87 octane in my street cars with no ill results whatsoever. Has anyone stopped to think about what the OMP does? Have you stopped to think why your rotary actually USES oil. It injects it into the rotor housing where it is mixed with the fuel during combustion. Doesn't the oil lower the octane rating of the fuel?

We actually use pre-mix in all of our race engines with 87 octane. Jim downing reccomended 87 with pre-mix. These engines are as close to a 2 cycle engine as they are a 4 cycle.

I will freely admit the RX-8 is new to me but I have a lot of experience with rotaries. So what's SO different in this engine to force me into using premium. It's not a matter of money, my M5 required premium, my turbo Volvo requires premium but my rotaries don't. Someone with some more experience then me please chime in and help me out.

 

We have similar histories. I always used regular in my race cars. The RX8 has higher compression rotors than previous engines. In the RX8, I have noticed my exhaust note changes. And some people report better gas milage, when using premium. Mazda recommends 91 octane gasoline be used. I doesn't say it's required.
As far as the pre-mixing, I just started pre-mixing with my RX7 in the last month. Some, on this site, have studied the Renesis engines that have recently been rebuilt and found wear on the center or apex seals & rotor housing. Engine oil seems to be injected more to lubricate the corner seals. I already have had 2 engines replaced and the car is still under warrenty. That is why I now pre-mix. This problem seems to have been corrected on the newest of the RX8's.

 

Premium gas all the way...want my baby to run smooth forever...