How to Convert a Car to Run on Vegetable Oil

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/rape 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.

Instructions

Difficulty: Moderate

1. 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.
2. 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.
3. 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 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.
4. 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.
5. 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.

Tips & Warnings

• In warm weather, the car can be started and run completely on vegetable oil.
• Make sure to keep your regular diesel tank just in case you may run out of vegetable oil or want to travel to a cooler climate.
• Purge the fuel line and fuel pump/injector with biodiesel or regular diesel every time you stop your engine just in case the weather turns cold unexpectedly.
• It’s possible to change the rubber seals on older diesel vehicles so that they too can be converted to run on vegetable oil.
• Consider using a fuel injector/piston cleaner every six months to remove any accumulated carbon deposits. To do this, just pour the 12-ounce bottle into the tank before you drive.
• Biodiesel is the only alternative fuel that has been tested completely for health effects based on the requirements of the 1990 Clean Air Act Amendments.
• Biodiesel is sometimes combined with standard diesel and sold under the label “biodiese.l” However, its benefits are relevant to the portion of pure biodiesel used.
• Straight vegetable oil (SVO) is any vegetable oil that can power diesel engines but has not undergone the transesterification process. The major constraint of using SVO is that it thickens at colder temperatures (below 25 degrees Fahrenheit), but it can be warmed up before reaching the engine's fuel injectors.
• It’s expensive to buy and use fresh cooking oil, but restaurants are often willing to donate their used cooking oil, which is commonly called Waste Vegetable Oil (WVO). Vegetable oil engine conversion kits include a heating system and usually a second gas tank to get around the cold weather issues. Like Biodiesel, SVO produces very low emissions. However, raw vegetable oil does not meet biodiesel fuel specifications and is not registered with the EPA, nor is it a legal motor fuel.
• Converting your car to run on vegetable oil can void any warranty you have on your car. Contact your dealer or manufacturer to find out.