Octane: All About the Ratings

There is a lot of confusion around the different grades of fuel available in the United States: regular, mid-grade and premium. Actually, they are all the same thing, except for one component — octane.

What is octane anyway? Octane is a hydrocarbon chemical compound that is added to gasoline to resist ignition by compression. As we move towards higher and higher performance engines, in turn, the compression ratio of these engines increases, and to cope with the pre-detonation (where the fuel ignites because of compression heat versus by the spark of the spark plug) requirements of these higher compression engines, higher and higher levels of octane are needed to keep the engines running smoothly.

So, there is no quality or purity differences between the different grades of fuel, just merely octane. While some engines have the ability to advance the spark timing of their ignition systems based on the detection of higher octane fuels, many do not — and the uninformed regularly put premium grade fuels into their tanks at a much higher cost when not necessary at all.

Do yourself a favor, stay informed and read your owner’s manual to determine the correct grade of fuel to put in your tank. Not only will it save you money, but you will know more about your vehicle — and knowledge is power.