Octane rating
•Octane number measures the antiknock quality of a gasoline. The higher octane number, the more resistant the gasoline is to knock.
•High compression engines require high-octane gasoline
•Before 1975, leaded gasoline was used for additive for anti-knocking.
•However, these day leaded was not allowed by reason of poison.
•Minimum Octane is 89 for normal SI engine.