Vegetable oil is a source of alternative energy and used as fuel in diesel engines and heating oil burners. The viscosity of vegetable oil is lowered for use in engines designed to burn diesel as fuel. Proper atomization of the fuel must be allowed for to avoid incomplete combustion and carbon buildup that can damage the engine. Waste vegetable oil (WVO) is oil discarded from use in restaurants. The dependence on imported petroleum and fluctuating fuel prices are the main reasons for the growing interest in using biodiesel, which is an alternative fuel made from vegetable oils. Straight vegetable oil (SVO) or raw vegetable oil (RVO) has also drawn interest because of their direct use as fuel. They are also appealing because SVO and RVO are available from US agricultural and industrial sources.
The disadvantage of using SVO is that it is much thicker than the conventional diesel or biodiesel and can damage vehicle engines, according to published engineering articles. It causes buildup of carbon deposits and has a negative impact on the engine lubricant. The very high boiling point and viscosity of SVO causes engine damage over a long period of time.
Motor engines are today designed with a focus on petroleum-diesel fuel. Vegetable oil will burn well in a diesel engine only if it is less viscous that can be attained by mixing with another fuel such as kerosene oil or by heating up to 160 degrees Fahrenheit. The benefits of vegetable oil fuel are that it is widely available and diesel engine converter kits are efficient as well. Air pollution is greatly reduced when compared to conventional fossil fuels. It is also claimed that the range of a vehicle improves dramatically with the use of this form of fuel.
The disadvantages are that the converter kit is expensive apart from installation expenses. An additional fuel tank has to be placed in the trunk, occupying premium trunk space.