Is running a car on cooking oil for real?

The old Mercedes Benz 240 D is a popular conversion car for cooking oil rides.

Many of us have seen the news reports or read stories about people who are dumping used cooking oil into their diesels. Veggie and biofuel diesels are cleaner than hybrids and represent a quick way to lower our dependence on foreign oil. All you need to do is dump used cooking oil or veggie oil into your diesel’s tank and go!


Well, there are several things that the consumer should know before buying a diesel and pulling up to their local “greasy spoon” to negotiate the disposal of their used deep-fryer’s juice (used cooking oil). It’s not quite that easy.

There is a difference between biodiesel and waste oil:

WASTE OIL: Diesel vehicles need to be converted to use waste oil. The process is fairly straightforward and can cost anywhere from $1,000 to $4,000 for a conversion kit. It is an easy job for a mechanic and those of you who are mechanically savvy will save thousands installing the system yourself over a weekend.

Your vehicle will need a separate fuel tank, separate fuel pump, redundant lines, switches, valves, gauges and a few other components for the conversion. Also, a fuel tank heater as there is a magical number for the veggie fuel’s temperature to maintain the correct viscosity (around 160 degrees Fahrenheit). Cooking oil is a jealous mistress.

Essentially, you are creating a new pathway to your engine for your veggie fuel. You must keep diesel fuel in its own tank with its own lines feeding to the engine. Some systems are sophisticated enough to direct the fuel delivery to your diesel engine that varies from petroleum based diesel (petrodiesel) to veggie fuel somewhat automatically. In diesels, you want the first fuel in and last one out to be petroleum based. This mitigates the potential for the veggie fuel to coagulate in the engine’s fuel system when the engine cools, potentially killing the injectors, fuel pumps, carburetors, even the engine.

There are various safeguards you have to adhere to in order to prevent fouling the system. Used cooking oil has to be filtered and tested (which is as easy a using strainers and a hot plate). Indeed, once these fuels begin to combust, you will smell like a rolling restaurant. Your vehicle is converting the veggie fuel into fuel all by itself.

Keep in mind, veggie oil and other potential fuels that have not met the tier I and tier II EPA safety requirements may not be legal in your state. This is to say that simply dumping a few gallons of used cooking grease and various veggie oils in your diesel may be illegal in your state. There are various provisions and regulations which you should research first.

Check out the second half of the cooking oil story tomorrow!

… and check out how much fun Roman and I ha, Andre the Russian mechanic and I have with this diesel!

Easily amused by anything with four wheels, Nathan Adlen reviews vehicles from the cheapest to the most prestigious. Wrecking yards, dealer lots, garages, racetracks, professional automotive testing and automotive journalism – Nathan has experienced a wide range of the automotive spectrum. His words, good humor and video are enjoyed worldwide.