So I recently bought my first RX8 the previous owner did an amazing job taking care of the car, he would use premium gas only he had it for 62k miles since 2005 would it hurt if i switched to regular 87 octane gas in my RX8?

 

why not just follow mazda's guidelines?

 

Yes. You'll get less fuel economy, and be risking blowing your engine.

Run the premium.

 

what are those guidelines?

 

To run premium. It says so when you open your fuel door to get to the fuel cap.

And in the owner's manual.

Give it a read, and look over the maintenance schedule, and get your 8 caught up to it.

Cheaping out in your car now, will lead to it being much more expensive down the road.

 

Yeah, I tried regular once - never again. In normal driving there appeared to be little difference, but under load at higher RPMs, there was pinging. The knock sensor feedback doesn't seem to have enough range to completely prevent pre-ignition with lower octane fuel.

 

alright thanks i havent actually opened my fuel door yet because i live in oregon its illegal to pump your own gas lol

 

Oh wow. Heh, glad I don't live there, I wouldn't trust people to premix my 8 right, haha.

But yeah, give your owner's manual a read through, you'll learn a few things about your 8.

 

The octane numeric grade for "Premium" depends on where you are in the country. When I did my cross country trip, I found several places where "Premium" was 89.

I personally found that my 8 has no problems at all with 89. I literally can not detect a difference between 89 and 91 or 93. With 87 it starts having issues.

Some people have run 87 in their 8s without issues, some swear by it, etc... I have a feeling that the better your engine compression the higher grade you are going to have to use. The people that handle 87 fine are probably low-ish compression.

The important bit if you are going to play around with what octane your 8 is fine with, is test with only a gallon or two in the tank. That way if you are too low, fill the rest of the way with something higher to raise the average octane so you are burning an entire tank of too-low octane. And if you do find what you can't run, DO NOT go full throttle high RPM until you bring it up. High RPM full throttle with too low of an octane = blown motor. Keep it light throttle and low rpm until you bring up the octane average.

 

Great Info thanks!

 

I use the plus ever since i bought the car in 07. Never really had serious problems with it. Anyway, its better to use what is recommended and your engine will love you for it...lol

 

Altitude affects the octane rating of the fuel.

I'm running 87 atm with no noticeable loss of horsepower. I also used it in my RX7's.

 

If a couple extra dollars per fill up is going to break your bank, getting an RX-8 was a poor choice.

 

It certainly can't help.
Considering everything, it's probably best to stick with premium. Like the 3-month oil change, think of it as insurance that costs way less than repairs.

 

It's around $3.50 more per tank for premium.
Go for it.

 

Thanks guys, yea it will deffinately not hurt my finances by spending the extra 5 bucks per fill up...