I would concur with everyone else about not burning wmo.
If you can find it in your area, try burning a "store" bought blend of diesel fuel with a B10 or B20.
Watch how the engine reacts to it. Then maybe try finding some blends that are more like a B50???
Don't know much about the 6.0 but I know it has some issues, but if fixed correctly think they run ok.
Problem with dumping some veg oil in the tank and filling it with diesel, it might not stay mixed, then you'd have a 100% veggie oil going through.
Not that we don't want you here, but try find a board like this, but mainly devoted to bio-diesel or veggie oil stuff, and then read, read like the wind.
If you do run some through this 6.0, lets us know how it acts or whatever happens.
Always like to hear about people trying new stuff.