by Mary Vance

Created on: November 05, 2008   Last Updated: November 16, 2008

Gasoline, whether to purchase premium or regular brings a wide range of opinions from consumers as well as automakers. Some owners feel that they are abusing their vehicles if they fill them with regular gasoline.

Regular gas has an octane rating of 87, mid-grade 89, and premium 91-93. Many stations now only sell two grades, 87 octane regular, and a regular and premium mix at an 89 octane rating. The price difference between the different grades usually runs between 20 - 40 cents. Octane rating is used to determine a fuels resistance to knocking. All newer model vehicles have a knock sensor that causes the engines computer system to automatically adjust for octane levels to avoid knocks. There is very little difference between premium and regular in regard to energy content. Both contain 111,400 British Thermal Units per gallon.

Most vehicles have very minimal, to no added benefit from using a higher octane fuel. The exception would be some older model cars, as well as high performance cars such as the Dodge Viper, Corvette, and other high performance superchargers.

This quote from the the Federal Trade Commission states, "In most cases, using a higher octane gasoline than your owners manual recommends offers absolutely no benefit. It won't make your car perform better, go faster, get better gas mileage or run cleaner."

Our long held belief that higher octane is better comes from many years of advertisements from the oil companies. The Federal Trade Commission filed a claim of "False Advertising" against Exxon in 1996, for their avid promoting of higher octane gas as the better choice. Part of Exxons settlement agreement with the Commission, was to produce advertisements stating that regular gasoline was the appropriate fuel for most cars.

Many oil companies still convey their message that their product is better because of the additives (detergents) their gas contains. The government mandates that all gasoline contain some of these additives. Some companies do add more of these additives than others.

Premium fuel sales bring in more revenue without much added cost for the oil companies to produce. Sales of premium gasoline accounts for approximately 15 - 20 percent of gasoline sales. When gas prices rise that percentage rate goes down.

Owners of high performance vehicles will need to purchase a premium, higher octane fuel. The rest of us that drive more sedate modes of transport to work and to our daily activities can rely on regular gas to carry us along.

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