What do the numbers 92, 95, and 98 mean at the gas pump?

[NadiaLee]

Gasoline grades 92, 95, and 98 represent different octane ratings of fuel. Higher octane gasoline has greater stability. Some vehicles require 92 octane gasoline, while others need 95 or 98 octane to prevent engine knocking. Here are the details: 1. 92 octane gasoline: This fuel has an octane rating of 92 and is suitable for mid-range vehicles (those with lower compression ratios). 2. 95 octane gasoline: Composed of 95% isooctane and 3% n-heptane. High-compression engines require high-octane gasoline; using low-octane fuel in such engines can cause abnormal combustion, knocking, poor fuel economy, and reduced performance. 3. 98 octane gasoline: This grade matches the knock resistance of a mixture containing 98% isooctane and 2% n-heptane. 98 octane offers superior anti-knock performance and power output while producing fewer harmful emissions.