Non-oxygenated gasoline refers to any gasoline that does not contain added oxygenates. According to the Utah Administrative Code, a fuel must contain at least 2 percent oxygen by weight to be considered oxygenated.
A fuel oxygenate is a group of chemicals that increases the oxygen content of gasoline, thereby increasing the octane content and allowing the fuel to burn more efficiently, according to the New York State Department of Health. These oxygenates are added to gasoline to reduce fuel emissions, and are necessary to meet the specific oxygen requirements laid out in the 1990 Clean Air Act Amendments, according to the American Petroleum Institute. The most commonly used fuel oxygenates in the United States are ethanol and methyl tert-butyl ether.
Gasoline oxygenates are able to reduce fuel emissions by cutting down on the amount of partially oxidized gasoline components that are released when the fuel is not burned efficiently, states the U.S. Environmental Protection Agency. The fuel oxygenates actually allow the gasoline to burn at lower temperatures, which reduces the amount of NOx, CO and hydrocarbon emissions. This is because the oxygenate increases the octane content of lower quality fuels. However, there are drawbacks to oxygenated fuel, such as the fact that it reduces fuel economy and engine efficiency.