Illustrated Glossary of Organic Chemistry

Octane rating (octane number): A measure of performance of fuel for internal combustion engines. Stated simply, a higher octane rating corresponds to more engine power and less knocking or other pre-ignition problems.

This pump offers gasoline with four different octane ratings (85, 87, 89, and 93) as well as diesel fuel.

2,2,4-Trimethylpentane (isooctane)   
Octane rating is based on a reference fuel composed of a mixture of 2,2,4-trimethylpentane (isooctane) and n-heptane.