[2divers]

Actually the trucking industry has been doing something similar for a long time. They use about 22 quarts of oil ( I think) a change. That would be a lot of wasted oil! They mix the old oil back in with the diesel at about a 1 to 50 ratio or so and burn it. The big difference between them and us is that they run the engine a lot longer and they keep the fuel more or less mixed in the tanks by the movement, stop and go. I think with a sailboat diesel it might settle out (may not depending on where you are on the hook)

I did a lot of reading when I researched Bio-diesel. A diesel engine will run on pretty much anything if you set the compression right and get enough heat. Some items have more energy than others (petrolium vs waste fry oil) but it still works.... Your buddy is right though, the real key is to get the engine good an hot and then burn your alternate fuel and then flip it back to diesel to get it running clean again.

The bad news is that unless it's been filtered you risk clogging your fuel injectors in a serious way...... Biodiesel can also clog your fuel injectors as a by product of it's use. The Biodiesel is a super solvent which disolves some of the crud from regular diesel in your lines and will pass it on the the fuel injectors where the will get plugged.... Can't win every fight.... I mix my 20 Bio to 80% diesel in my car. Runs great and I don't put as much cash in the oil companies pockets. (ok it's not a lot, but the only way I can vote there is with my pocketbook!)

2divers