What kinda octane gas do you use?

[FirebirdGT]

Mobil 89

320 miles between refills.

[Darknight]

Actually, I took ChemCom, but we learned those things anyway. We spent a lot of time on petroleum and its properties. Perhaps the most useful science class I ever took.

DK

[Arctc Wolf]

87 at exxon/mobil/shell/76/chevron. I have whisper lid, FTRA, K&N filter, removed maf screen, and 3" cat-back exhaust.

[zlexiss]

Some fuel for the octane fire:

http://www.caranddriver.com/xp/Caran...e_gasoline.xml

Summary: putting premium in cars designed for regular doesn't help a bit. Putting regular in cars designed for premium takes about 15% off the engine due to knock retard, though it's still driveable.

Premium gas generally contains slightly less energy per gallon than regular, due to octane boosters like ethanol and MTBE being less energy dense than the base gasoline blend.

That said, I go midgrade with my HPP3 set to run on regular anyways :)

[dstrbd1]

i've almost always used the midgrade (about 89) in my car, but recently i've started using premium, in part because of my tps tec which advances the timing. i also was having a problem with an egr code coming on and going off when i went back to mid for a while, but back onto premium the code doesn't come up at all.

[MotorHead69]

89 I used to run 87 till gm reprogrammed my car and it runs like *** if I put the low grade in my car

[12secondv6]

Back in the day when I was close to stock I tried 87 but pinged.
Normally I should NOT ping.
I ended up always running 93.
Now I run anywhere between 93 for daily use, 94 before race day, 100 very rarely on high nitrous shot day's

[camaro_speedemon]

Used to use 93, then switched to 87 because of gas prices and I actually get a little bit better milage with 87 than 83. On the other hand, I have noticed a performance loss going to 87. I have yet to head to the track and see my theory is true. Since I switched, I can feel my motor stutter a lot more when I jump on it. I had this problem before, but it got worse when I switched to 87. Once gas prices drop again, or I get a better paying job, 87 is going in. I can't justify paying 1.90 for 93 :eek:
Edit: As for milage, I'm getting about 23MPG mixed city/highway. I also noticed a couple MPG increase when I got my high-flow cat.

[ March 07, 2003: Message edited by: camaro_speedemon ]</p>

[gt1953]

I use 87 and generally get 300 or so per tank you guys with the low mileage must really stomp on it or let it idle for lllooonnnggg periods. At the current fuel expense I want mileage...I still can pass when I want to.