I just find it amazing that a pre-85 stock diesel engine will run straight waste oil with no modifications whatsoever. And it sounds like the maintenance issues are minor. Of course, I wouldn't have much luck doing that up here in Seattle, but when I get down to southern Cali at the end of this year, I may just give it a shot.

What is the advantage to converting to bio-diesel if the waste oil gives you the same mileage as standard diesel?