Reprinted from The American Petroleum Institute

Octane: Making the Right Choice at the Pump

At the grocery checkout, the question is paper or plastic. At the pump, it’s 87, 89 or 93. These numbers relate to the octane levels found in the three most common grades of gasoline.

Octane helps protect against engine knock — uncontrolled combustion that results in knocking or pinging sounds which can damage your engine over time. Your car’s owner’s manual should tell you which grade of gasoline is recommended for your vehicle. You might also consider the following:

·        If you use gasoline that doesn’t have enough octane, engine knock could, over time, damage pistons and other engine parts. If your car has a knock sensor, it will compensate by slowing spark timing. Your engine will be protected, but possibly at a slight and sometimes noticeable loss in power and acceleration. Roughly half of today’s vehicles are equipped with knock sensors.

·        Most cars give optimum performance on regular or mid-grade gasoline. If you’re buying premium and your car’s not running any better than it does with a lower-octane gasoline, you’re probably wasting money. However, some cars may operate better on premium because of additives. Additives, which are found in all gasoline, keep engines clean and make them run more efficiently.

·        Driving habits, a vehicle’s mileage, and climate and geography can affect how gasoline performs in your car. Octane requirements tend to increase with mileage, at least through the first 15,000 to 20,000 miles. And a car hauling heavy loads over hills requires more octane than the same car driving on level roads. On the other hand, many older vehicles need less octane at higher altitudes, such as the Rocky Mountains.

The best advice is: try different gasoline, observe how they perform in your car, and pick the one that meets your needs.

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