Butane is added to gasolines to raise their octane levels.

For the oil companies the addition of lead to fuel provided a simple and inexpensive way to vary octane levels.

Deciding on what's best to eat is like settling on the right octane level for your car.

The problems of all five aircraft were thought to have been caused by fuel with a low octane level.

Looking for more information on selecting the right octane level for your car?

The lead helped to raise the octane level, which reduces engine knock.

Check your owner's manual to determine the right octane level for your car.

How can you tell if you're using the right octane level?

The higher the octane level, the more efficiently the fuel burns.

The manual should say what octane level is required.