or LPG, mixture of gases, chiefly propane and butane, produced commercially from petroleum and stored under pressure to keep it in a liquid state. The boiling point of liquefied petroleum gas varies from about −44°C to 0°C (−47°F to 32°F), so that the pressure required to liquefy it is considerable and the containers for it must be of heavy steel. When prepared as fuel, LPG is largely propane; common uses are for powering automotive vehicles, for cooking and heating, and sometimes for lighting in rural areas. LPG is an attractive fuel for internal-combustion engines; because it burns with little air pollution and little solid residue, it does not dilute lubricants, and it has a high octane rating.