gasohol, a gasoline extender made from a mixture of gasoline (90%) and ethanol (10%; often obtained by fermenting agricultural crops or crop wastes) or gasoline (97%) and methanol, or wood alcohol (3%). Gasohol has higher octane, or antiknock, properties than gasoline and burns more slowly, coolly, and completely, resulting in reduced emissions of some pollutants, but it also vaporizes more readily, potentially aggravating ozone pollution in warm weather. Ethanol-based gasohol in which the ethanol is made from corn is expensive and energy intensive to produce, and can damage rubber seals and diaphragms and certain finishes if the ethanol is present in higher concentrations. Since 1998, however, many American automobiles have been equipped to enable them to run on E85, a mixture of 85% ethanol and 15% gasoline. Methanol-based gasohol is also expensive to produce and is toxic and corrosive, and its emissions produce cancer-causing formaldehyde. See also automobile.