For the past year i've owned my car I have put nothing in it but 85 octane. Well the other day one of the gas stations in town that I normally get my gas at was selling 91 octane gas for the same price as regular. So I decided I would put some in my car. Well so far i've but about 15 gallons through the tank and it seems to run better than with the 85. How would this be possible with a car that only needs the minimum octane? If the minimum octane gas wasn't doing it'* job wouldn't it ping or knock. My car does nothing like that on any of the gas i've been putting in it. Maybe it'* the fact that the weather is so much colder now that it just seems to run better than when it was warmer. Also it seems to get better mileage as well. I'm gonna fill my car up tommorrow and see if it actually does get better mileage. Anybody have any thoughts on this? I don't wanna be wasting money on high octane gas that my car doesn't need.

I've never had pinging at anytime so should I just stick with the 85 then. Or is it possible that using the 85 it'* too low a octane and it was pinging and the computer changed the timing? If that'* the case then is this why it'* running better on 91 because it'* not retarding the timing?

Don't keep switching back and forth, you get better milage if you stick with one, but i run 89 in mine. It seems to run better at my lakeville gas station i use, and it'* the same price as 87 in mankato.

All i'm trying to figure out is if I run the lowest octane possilbe the computer is gonna keep it from pinging by retarding the timing. So therefore i'm losing power. Which means I need to go to a higher octane which will keep from retarding the timign and therefore i'll have more power again.

Octane also goes with how much horsepower you are producing. Thats why cars with higher horsepower require higher octance. The computer though will only retard the timing if it detects that the motor is pinging or knocking. If this still happens running on low octane then I would go with the next step higher octane. The lowest octane sold here is 87, if 87 isnt available I go closest above 87 .

I use 89 always in mine, It gets alot better gas mileage than it did when I first bought it and it was running 87. I always found that the higher the octane the better the car runs. My advice to you is that if you can afford it, I would use nothing less than 89. You should see better gas mileage develope within your first or second fill up of 89. Plus your engine will thank you for it, trust me.

I was running 89 in the 89, now I run 91 or 93 in the '96

If the car asks for premium its for a reason (L67 and L47 N*) but the LN3, L27 and L36 don't require high end octane.

In the end, use what is best for your car

Elevation will play a factor in how your car runs on what octane. I dont know the physics behind it though.

Less is needed at higher altitude. 85 octane here where i live is equal to 87 elsewhere.