Originally posted by detroitrice
The octane really doesn't do anything that noticeable as far as performacne goes, even racing blue, doesn't really effect it all that much. However, it's going to be along term thing, you aren't going to notice it immediately as much as you will over the long term. For example, if you continuously use premium gas, you'll notice that your car will shift smoother, knocking will be eliminated, and your car will accelerate quickly and quietly. You'll be able to tell a substantial distance in performance after a good 2 weeks of use, just because your fuel system will be cleaned out, and the better your fuel system works, the more efficient it will be.
No, No, No...not true. That's what the gas companies would like you to believe. All gas is required to have detergents to "clean out" your fuel system. Octane is simply a rating that tells you how fast the fuel burns.
Bottom line: if your car is not tuned for premium or mid-grade you are literally blowing money out of your tailpipe. If you are using a higher grade gas to hide engine pinging, you are trying to avoid a bigger problem.