Quote:

High octane gas can create unnecessary repairs

A "knock" or "ping" occurs when part of the fuel-air mixture in one or more of your car's cylinders ignite spontaneously due to compression, independent of the combustion initiated by the spark plug.

If your car runs poorly or "pings" on the grade of gas recommended, it may need servicing, rather than using a higher grade of gas.

If switching to high octane improves mileage, it may mean that your engine, or its control system needs repair.

The higher the octane, the higher the price.

Good Luck

4-Sure

 

Very informative thread.
Thanks for posting and members inputs.

 

i always use 87 octane unless its in the truck than i use a real high octane due to the way the motor was built

 

i would only run whats recommened, unless like other members said your car has mods done to it or a tune.

 

Just an FYI to clarify for you, incase I mislead you JAMAO, YOUR Monte requires premium 91 octane fuel because you have the supercharger.

Break down for Monte's and engines:

87 octane can be used in the following engines as factory spec:
-3100 V6
-3400 V6
-3500 V6
-3800 V6
-3900 V6

91 Octane or higher is factory recommended fuel for these engines:
-3800 Supercharged V6
-5300 V8

 

i have the 3500 and always use 89 idk why but it makes me feel better about the quality. i asked the dealer and they say that they recomend 87 for my car , but 89 wont hurt and may increase gas mileage. one thing ido know for sure they told me not to run 93+ for the same reason kidspace said.

 

You didn't mislead Michael.
You've explained this to me before ^.^ Thank you!
The pumps here are 93, only WaWa gas stations around here carry 91.
My dad on the other hand is stubborn, he always .. always .. ALWAYS puts 93 on his Corolla and F-F150 OUCH!
He feels its the "best". >.>'

 

If you are boosted I would run the highest you can run because stock L67s knock usually on 89/91

 

You can get the laptop program and scan your car for knock retard (when the engine detects premature detonation of the fuel I believe.) The octane of the fuel is the ability of the fuel to resist a premature combustion. Thus, if you're having problems with premature combustion, a higher octane gas may be more efficient. I assume going to far, as in 110 octane, may become too resistant and not detonate right for you... but I could be wrong on that.

I've run 87 and 93. The 93 octane gets me around 30-31 highway, and the 87 runs me around 28-30. So for the price difference, it comes out around the same! :-D

Back in the '60s and '70s, fuel really made a difference. The brands and grades, especially back in the leaded fuel days, could be a HUGE difference!!! However, today, I've been by the fuel farms... and all of the gas is nearly the same!!! All of the tankers line up at the same huge drums (like the size of a large office building or bigger) and fill them up!! In many states, all of the fuel is now partially ethanol. This is where a difference may come. If your state is all ethanol, then the only difference in any of the grades or brands of gas is packets of detergent. There are less contaminants and peraphins now than there were back in your dads day.... so you can depend much more on the quality of your fuel today than he could yesterday!

 

Lol, not ''boosted'', stock for the mean time.