Vegetable oil can be used as an alternative fuel in diesel engines. When vegetable oil is used directly as a fuel it is referred to as straight vegetable oil (SVO). Waste vegetable oil (WVO) can also be used as a fuel after filtering.
Conventional diesel engines can be modified to ensure that the viscosity of the vegetable oil is low enough to allow proper atomization of the fuel. This prevents incomplete combustion, which would damage the engine by causing a build-up of carbon. Vegetable oil can also be blended with conventional diesel or processed into biodiesel.