Gasoline, also called petrol, is a flammable liquid fuel primarily used to power internal combustion engines, such as those in cars, motorcycles, and small machinery. It’s derived from crude oil through a refining process that involves distillation, cracking, and other chemical treatments to separate and enhance its components. Chemically, gasoline is a mixture of hydrocarbons, compounds made of hydrogen and carbon atoms, typically containing 5 to 12 carbon atoms per molecule, with common ones like octane (\(C_8H_{18}\)) being key for performance.
It’s stored and sold in various grades (like 87, 89, or 91 octane in the U.S.), which indicate its resistance to knocking—premature combustion in an engine. Additives like ethanol (often up to 10% in many blends) are mixed in to boost octane, improve combustion, or meet environmental regulations. Gasoline’s energy content is about 33.7 megajoules per liter (or 120 MJ per gallon), making it a dense, portable energy source, though it’s less efficient than diesel in some applications.
Octane Rating (U.S. Standatd)
Regular Gasoline (87 Octane) - The most common and least expensive type, suitable for most everyday vehicles.
Mid-Grade Gasoline (89–90 Octane) - A slightly higher octane fuel, recommended for some vehicles that require a bit more power and efficiency.
Premium Gasoline (91–94 Octane) - High-octane fuel designed for performance and luxury cars, turbocharged engines, or vehicles that specify premium fuel.
By Ethanol Content
E10 (10% Ethanol, 90% Gasoline) - The most common gasoline blend in the U.S.; works in most vehicles.
E15 (15% Ethanol, 85% Gasoline) - Approved for newer vehicles (2001 and later) but not recommended for older engines.
E85 (85% Ethanol, 15% Gasoline) - Used in flex-fuel vehicles (FFVs) designed to run on higher ethanol blends.
Special Gasoline Types
Reformulated Gasoline (RFG) - Designed to reduce emissions and pollution in areas with high smog levels.
Non-Oxygenated Gasoline - Ethanol-free fuel often used for classic cars, boats, and small engines (like lawnmowers).
Aviation Gasoline (AvGas) - Special fuel used for small aircraft engines, not suitable for regular vehicles.
Racing Fuel - Very high-octane gasoline (100+ octane) used for professional racing and high-performance vehicles.
