Waste vegetable oil (WVO) is vegetable oil that is recycled, typically from restaurant fryers and is used in diesel engines. Most users reclaim WVO from their local restaurants for free. Many users of this fuel modify their engine compartment to provide heating for the WVO or SVO to decrease its viscosity.
Straight vegetable oil (SVO) is vegetable oil that has never been used. Biodiesel is not the same as SVO or WVO, but it can be made from both through a chemical reaction.