Regular Unleaded in GT model??

[Evanshall]

the first few times i fueled the Vibe GT, i filled it with regular, now i havnt seemed to have had any problem with the vehicle, all except the acceleration doesnt seem as fast as i think it should be able to go, its supposidly a mid 7 0-60 car, im having trouble getting around mid 8s but thats with bad launches basically every time, is all this normal, and is there anything i should do sincei accedently filled the vibe GT with regular, it was a while ago, but is there anything i should still do?? and did you do anything bad possibly?

[Jahntassa]

As far as i've heard, you can run the occaisional tank of less than 91 octane, but try not to. The more you run it, the worse off things can get. (As Silver said)Try writing "Premium only" on the gas cap, I think it's already printed inside the gas door..

[Evanshall]

i have, im just asking what generally gets damaded if anything when you accedently did do the one or two times on regular?? and should i be able to notice it in regular driving conditions, or is it more suddle then that?!?and should it directly and permanently (even if only accedently adding it 2 times) effect proformance??

[dsegundo]

maybe you fouled some plugs because you used the regular unleaded stuff?

[ragingfish]

Try running a bottle of Techron through it. That should clean out any crap left behind by the regular fuel...Then see if things improve...

[Evanshall]

i just ran 7.89 in 5-60, was going easy on the clutch as well, so if i poped it i coulda probably dropped another .2 and if i could learn how to launch maybe another .3, so obviously its my bad launches that are the cause of slow 0-60s!!! (previously 9.12,alot of squeling of tires and no moving forward)ill keep in mind the techron, the engine seems to be fine, now that i know t hat its still badass, i will proceded with trying to mod it

[ragingfish]

I run a bottle of techron through ever 10-15000 miles anyway, just as preventative maintenance. Only a few bucks a bottle...Or if you have a chevron station around you, i believe all grades of their gasoline have the techron additive in it already. just fill up with their stuff.

[Jahntassa]

I do need to report that after running 98% BP Ultimate through my GT, that the recent tank of Chevron I put in, absolutely sucked. Only got 17 MPG, been averaging 20-21 on BP. (Lots of City driving..bah!)

[5lbsofswisscheese]

The higher octane gasoline is necessary because of the high compression ratio on the GT's engine. The octane rating on gasoline measures nothing more than its resistance to knocking/pinging. Knock is caused by the gasoline spontaneously combusting inside the cylinders, before it is ignited by the spark plugs. This is obviously a bad thing, and can potentially cause damage to the internal parts of your engine. The higher the compression ratio in your engine, the more likely this spontaneous combustion is to occur.GM recommends the 91 octane gasoline because they feel there is an increased risk of knock with regular or midgrade gasoline. Higher chances of knock means more warranty repairs. It's not an issue of deposits in the engine or anything. The higher octane is necessary simply to avoid knock.If it didn't ping while you ran the regular gas in it, I would not worry about it. Just be more careful about what you put in the car, in the future.

[futseal04]

You probably could run regular all the time if you wanted to. Knocking (or detonation) occurs 99% of the time when you are running the engine at a high RPM under full throttle. My Cobra required 91, but in some mountain states, you could only get 89. It was fine til i went to pass an 18 wheeler and hit about 5200, when i started to hear light pinging. Just cruising, (light acceleration, constant speed) you could run it, but I would carry a bottle of octane booster just in case.

[5lbsofswisscheese]

I was thinking that, actually. I just didn't want to tell someone else to do it. The higher octane is really only needed above 6800 (or wheverever it happens at) where the engine adjusts the valve lift and timing. I rarely if ever push my car that hard, so I normally put midgrade or regular in it. Never had so much as a single ping with my 03 GT for the 2 years I had it. Of course, if I anticipate pushing it to the redline, I make sure I have a high enough octane in the tank.

[MadBill]

Im sure the Vibe GT, like virtually all modern engines, has a knock sensor that retards the spark timing when it detects detonation. Unless the fuel is severely deficient, you likely won't hear any knocking or pinging, but the retarded timing will affect performance and probably economy, since most engine computers include a "low octane" spark table which has less spark advance and which is used when the sensor repeatedly detects knock. Once you return to the specified high octane fuel, the system notices that knock is no longer being detected and reverts to the "high octane" spark table.As an example, since it's mostly just used around town I occassionally use mid-grade in my wife's supercharged Buick Park Avenue. More often than not she soon asks me what grade I used because: "it feels kinda sluggish and I hear a faint pinging sound when I'm going up hills..."

[ragingfish]

My $0.02.DON'T buy a car that requires premium if you're not willing to pay for it.If you want the power, pay the price.The engine is designed for 91, if you put in less than that on a regular basis, you're only hurting yourself.

[goodvibe]

And pontiac has to recommend the fuel that they need to use to meet fuel mileage and horsepower specs. Both will be worse on lower octane and less advance so you won't be saving very much by buying regular anyway.