Why not just use the grease directly in a Diesel engine instead of processing it into biodiesel?
In a pinch, you can do this and some Diesel engines will run on straight grease. However, we do NOT recommend trying this in your mother’s beloved Mercedes. Most Diesel engines are not designed to run on straight vegetable oil. In tests done at the University of Iowa and in Europe, the insides of many diesel engines “coke” up and simply stop working when running on straight vegetable oil. We use biodiesel because it is thinner and more combustible than straight vegetable oil. There are some simple modifications you can make to the engine’s fuel system in order to run the engine on straight vegetable oil (new or used). Complete directions for making these modifications will be given in the second edition of From the Fryer to the Fuel Tank, available in June 1999.
