Gasoline

Gasoline (/ˈɡæsəliːn/) or petrol (/ˈpɛtrəl/) is a petrochemical product characterized as a transparent, yellowish, and flammable liquid normally used as a fuel for spark-ignited internal combustion engines. When formulated as a fuel for engines, gasoline is chemically composed of organic compounds derived from the fractional distillation of petroleum and later chemically enhanced with gasoline additives. It is a high-volume profitable product produced in crude oil refineries.^[1]

The fuel-characteristics of a particular gasoline-blend, which will resist igniting too early—and cause engine knocking and reduce efficiency in reciprocating engines—are measured as the octane rating of the fuel blend; the gasoline blend with the most stable octane rating then is produced in several fuel-grades for different types of motor. Tetraethyl lead and other lead compounds are not used in modern automotive gasoline, except in aviation, off-road motor vehicles, and racing car motors.^[2][3]

Gasoline can enter the Earth's environment as an un-combusted liquid fuel, as a flammable liquid, or as a vapor by way of leakages occurring during its production, handling, transport and delivery.^[4] Gasoline contains known carcinogens.^[5][6][7] Gasoline is often used as a recreational inhalant and can be harmful or fatal when used in such a manner.^[8] When burned, one liter (0.26 U.S. gal) of gasoline emits about 2.3 kilograms (5.1 lb) of CO₂, a greenhouse gas, contributing to human-caused climate change.^[9][10] Oil products, including gasoline, were responsible for about 32% of CO₂ emissions worldwide in 2021.^[11]

On average, U.S. petroleum refineries produce about 19 to 20 gallons of gasoline, 11 to 13 gallons of distillate fuel diesel fuel and 3 to 4 gallons of jet fuel from each 42 gallon (152 liters) barrel of crude oil. The product ratio depends upon the processing in an oil refinery and the crude oil assay^[12] (see § Etymology).