Diesel engines can run on three basic types of fuel: petroleum diesel, biodiesel, and straight vegetable oil (SVO). Diesel fuel produces carbon dioxide, pollution, particulates and sulfur emissions and increases reliance on foreign oil because it comes from petroleum. Any diesel engine can run on biodiesel. Biodiesel is a clean-burning fuel made from domestic, renewable plant sources, such as oils from vegetables, peanuts, soy beans, canola/grape seeds, hemp seeds and some grains. It has undergone the process of transesterification, a simple chemical modification of ordinary vegetable oil that makes the fuel usable in diesel engines and keeps it from thickening at colder temperatures.
Start with a modern diesel engine. Nearly any newer diesel engine can be converted to run on vegetable oil as long as it doesn’t have rubber seals in its fuel system (only older diesels use rubber seals). The rubber seals will deteriorate when exposed to vegetable oil over time because vegetable oil acts as a solvent.
Install a vegetable oil fuel conversion kit or have a mechanic do it. You should keep the original gas tank to hold regular diesel or biodiesel fuel for cold weather. Install a second tank for vegetable oil; these sometimes go in the trunk. The conversion kit should include hoses from the car’s radiator to the vegetable oil tank to heat the oil via a heat exchanger before it enters the final fuel filter and injectors inside the engine compartment.
Get vegetable oil. New vegetable oil is easiest to acquire but very expensive. Restaurants will often give you their waste oil for free. Chinese and Japanese restaurants are best because their oils comes out cleanest. The oil should be amber in color. Oil from other types of rest restaurants may also be suitable but could require more filtering to remove food particles. You will need a few containers for transferring the oil from the source to your filtering destination. The five gallon jugs that the restaurants receive the fresh oil in work fine. Restaurants are usually happy to give you these containers since it saves them disposal fees.
Filter the oil. Use filter bags that are rated to 0.5 microns thick. To increase the life of your filter bags, first allow the oil to sit in a barrel for about a week to let particulate matter settle to the bottom. Then, pump or scoop the oil into a filter bag suspended above a fresh empty barrel from the top of the barrel (since most of the food particles matter and possible water is at the bottom). Start your engine using regular diesel or biodiesel fuel from the normal gas tank. Once the engine and vegetable oil are warm (after about 15 minutes depending on weather), switch to allow the vegetable oil to flow into the fuel source.
Switch back to diesel or biodiesel a few minutes before you stop your engine for any time (about 10 minutes depending on the temperature) to make sure the vegetable oil is purged from the fuel line and injectors so that they don’t become clogged when the engine cools.