John Paul, AAA Northeast's Car Doctor, answers a question from a reader who recently visited a service station offering both 87 and 88 octane gas. The post Comparing 87- vs. 88-octane gasoline ...

87 octane gasoline, often called "regular" gas, is one of the most commonly used fuels in the United States. But what gives it that 87 rating is a word you've probably heard a time or two: Ethanol.

You might have noticed that some gas stations occasionally offer specials on unleaded 88 octane gas—also known as E15—which contains 15 percent ethanol. Ethanol is an alcohol that’s derived from corn.

If you've ever fueled up in Colorado, you might have noticed something unusual about the gas octane ratings at the pump – specifically, the availability of 85-octane gasoline. This lower octane fuel ...

The answer is yes: You can mix 87 and 91 octane gasoline without blowing your engine to hell. With that out of the way, let's discuss what mixing different octane fuels does to your engine in terms of ...