The answer to this question depends on the type of car you drive and how much you would be willing to invest in order to put used vegetable oil in your tank. If you currently drive a vehicle with a standard internal combustion engine, then the answer is no, your car will definitely not run on used vegetable oil. If you drive a vehicle powered by a traditional diesel engine, the answer is a little more complicated. An unconverted diesel engine should accept biodiesel, or methyl ester. Biodiesel is the result of putting animal fat or vegetable oil through a catalytic reactive process called transesterification. A diesel engine which has been converted to accept waste vegetable oil (WVO) will run on used vegetable oils under the right conditions.
The diesel engine designed by Rudolf Diesel originally used peanut oil as a fuel source, although it would not be considered a biodiesel fuel today. When petroleum waste became more commercially viable in the 1920s, petroleum diesel fuel became the standard and the development of better vegetable-based diesel fuels took a backseat. It was only when the fuel crisis of the 1970s arose that alternative bio-fuels such as used vegetable oils became a topic of discussion among the environmentally conscious.
The idea of using used vegetable oil as a fuel source may still sound a little foreign to people who are accustomed to visiting a gas station regularly for their fuel. In fact, the use of used vegetable oil through a conversion kit is still technically against federal laws concerning emissions. Enforcement of those laws has not been very strict, however. Owners of diesel-powered vehicles can purchase conversion kits which contain a heatable tank for used vegetable oil storage. The used vegetable oil must be heated before it can be safely introduced into the engine itself, and a secondary supply of traditional petroleum diesel or biodiesel must be used to start the engine and purge the used vegetable oil from the fuel line before shutting the car off.
A number of sources for used vegetable oil exist in many cities, including restaurants, food processing plants and commercial or institutional cafeterias. New vegetable oil can also be used, but the retail cost of straight vegetable oils can be prohibitive. An agreement to collect used vegetable oil can be struck between the car owner and a local business, or permission may be granted to siphon off a tankful of used vegetable oil from a waste tank. Many businesses which generate large amounts of waste cooking oil contract with local waste management companies to remove it from the premises, so it is also possible to enter into an agreement with the waste management company or one of its clients. Used vegetable oil, especially the golden yellow variety often found in Chinese restaurants, is considered to be quite a valuable commodity among the environmentally aware.