super vs regular

[Laptop_geek]

My cobalt ss and my z28 dont run nearly as good on regular. I always use 93 in them. Nothing can tell you better than how your car runs.

Both of those engines are designed to run high octane fuel.

The only reason you should use high octane fuel is if the engine needs it, otherwise your paying more for fuel that has less energy per gallon. Doesn't make much sense to run the high octane fuel unless the engine your running it in is able to make some type of use of it. Most engines that are turbocharged, supercharged, or are high compression will specify high octane fuel. The reason is the same for all, high octane fuel is able to be compressed further before predetonation or pinging. There are lots of thermodynamics that goes into it all, but that's the easy answer.

[Cuda 69]

The way a very good scoot mechanic explained the regular/super differences to me ,was,use regular in air cooled scoots,because high test burns very hot and could do some major damage to your valves(burnt valves). He said using regular gas acually helps keep your air cooled engine cooler.He also explained that today's gasoline sucks. So take it for what it's worth.

[T99Ford]

Nope. More likely to burn an engine down on regular, since regular has a lower burn point. Octane is entirely related to burnability as was previously stated. Higher compression needs more burn resistan fuel to prevent pre-ignition. Period. The idea is to run the lowest octane you can and still prevent pre ignition, and thereby get the most power. For instance, I will sometimes run premium in my bikes (not 11's) during the best of summer, and use lower octane as it cools off, since the combustion chamber is running cooler. I can get away with low octane for a long time before ping is a problem. Likewise, I've run 85.5 octane pump gas in nitrous fueled snowmobiles, provided it was really cold and I was running over 8000 feet above sea level (less air at altitude = lower compressed gas in chamber and cooler compressed gas temp.

It's not really all that complex of a system, just knowing what you are actually doing.

[Cuda 69]

so what your saying is: lower octane in cold weather,higher octane in summer? I got some bad advice from someone I know,thanks.

[T99Ford]

Octane makes a big difference in useable horsepower. But it also serves a valuable purpose for engine longevity. Run the lowest you can without preignition, and you'll be maximizing your fuel. To be honest, I don't think it makes a lot of difference on the 11 since compression is not crazy, especially on original 30 year old engines. But it may be a player. As a rule I'd avoid premium in it until the very hottest parts of the summer, especially if you are riding hard, or sitting in traffic a lot where cylinder temps will rise.

[jetmechmarty]

I often buy premium fuel because often that is the only grade available without ethanol. Ethanol is bad news and 93 Octane won't hurt a thing.

Mike, that 91 octane sticker refers to research oc.tane. Today we use R+M/2. 87 octane is fine

[T99Ford]

+1 on premium to avoid ethanol...the octane is minor compared to that!

[TheFrugalTech]

I bought a '98 Cougar in May of '97. It was one of the first 2 that hit the lot across from my office. I bought the one with all the options and left them the crappy stripped down one to show.
Anyway, I remember there being a sticker inside the gas door or maybe it was right on the cap, that said to use 87 octane only. A few months later it is broken in properly and I decide to fill up on 93 premium.
The car ran like crap. One of the guys at the dealer said those cars keep a running memory on how they run most efficient. Changing up the gas threw everything off since the program assumes you are always running 87. He reset something and it ran fine the rest of the tank, he told me to stop back in when I ran that tank out and he reset it again. Never ran anything other than 87 in that car again.