"...biodiesel is not quite as simple as pouring deep fat oil in the tank. It has to processed to raise the octane and remove the glycerin, waxes and food particulates."
Bio-diesel is cool. Back in 2000, I made it all summer long. It runs good in a diesel, and smells pretty good, too.
A little lye and methanol mixed together to make methoxide, and filtered vegetable oil... mixed together, and left to settle for a minimum of 8 hours... bio-diesel.
One needs to also make sure that all of the gaskets can handle the small amount of alcohol in bio-diesel - otherwise they get eaten, and problems ensue. Newer vehicles like VWs (since about 1992 or so) already are using alcohol-resistant gaskets and fuel lines, so they are okay for bio-diesel.
There _is_ a way to run straight vegetable oil in a diesel engine... you just have to pre-heat it to about 175-degrees F before you feed it into the diesel engine. It is also required to start and stop the diesel engine with regular diesel (or bio-diesel), though - so one needs two fuel tanks and a 'switch' so that the fuel tanks can be switched accordingly.
Regards,
Jim TX