A converted diesel car can run on straight cooking oil.
There are several ways to use cooking oil as a fuel in a diesel engine. Straight vegetable oil (SVO) can be used, but your engine must first be converted to use it. SVO is more viscous than petroleum-based fuels, so it will not run properly through a regular diesel engine. Biodiesel is another option and can be used in a regular diesel engine. This is usually more expensive than plain waste cooking oil and needs to be processed first. Many different conversion kits exist and will save you money over the lifetime of your car.
1. Verify with the conversion kit manufacturer or your mechanic to find out whether your vehicle can be converted to run on cooking oil. Older vehicles usually cannot be converted. Collect enough vegetable oil to fill your tank. Filter the oil through a coffee filter or filter bag to remove any particulates.
2. Determine if you will be installing the conversion kit yourself or seeking professional help. There are several different conversion kits available from different companies, and each comes with its own set of detailed installation instructions. If you are unfamiliar with working on cars, it is recommended that you take your vehicle to a mechanic to install the conversion kit for you. The conversion kit will include a controller, an extra fuel tank to keep the vegetable oil separate from regular diesel (which you’ll still be using), a fuel heater, a heat exchanger, separate SVO fuel lines and an electric switch.
3. Wait a few minutes, after you start your car, for the fuel to heat up before driving it, especially in colder temperatures. Your vehicle will start up and power off using regular diesel fuel, and it will switch to the vegetable oil while driving. Some conversion kits will do this automatically, but with some you’ll have to do this yourself. If your car will be stopped for an hour or more, switch back to regular diesel about 10 minutes before the end of your drive.