GASOLINE

Gasoline is a highly volatile flammable liquid hydrocarbon mixture used as a fuel for internal-combustion engines. Acomparatively economical fuel, gasoline is the primary fuel for automobiles worldwide. Chemicals, called additives, such as lead, detergents, and anti-oxidants, are mixedinto gasoline to improve its operating characteristics.

Antiknock additives are used to slow down the ignition and burning of gasoline. This action helps to prevent engine ping or knock (knocking sound produced by abnormal and excessively rapid combustion). Leaded gasoline has lead antiknock additives. The lead allows a higher engine compression ratio to be used without the fuel igniting prematurely.

Leaded gasoline is designed to be. used in older vehicles that have little or no emission controls.

The fuel used today is unleaded gasoline. Unleaded gasoline, also called no-lead or lead-free, does NOT contain lead antiknock additives. Congress has passed laws requiring that all vehicles meet strict emission levels. As a result, manufacturers began using catalytic converters and unleaded fuel.

The properties a good gasoline should have are as follows:

• Proper volatility (how quickly the gasoline vaporizes)
• Resistance to spark knock, or detonation
• Oxidation inhibitors to prevent formationof gum in the fuel system Antirust agents to prevent rusting of metal parts in the fuel system
• Anti-icers to retard icing and fuel-line freezing
• Detergents to help keep the fuel system clean
• Dye for identification