To MAXRPM above - Biodiesel is not a Frankenstein experiment. There is a service station just down the road from me that sells B2 - B20 and you can order up to B100 from a distributor a few miles away. VW released a statement that up to B5 in it's new TDIs is ok. "Alternative" doesn't always have to mean "scary" or unfounded.
We've all seen the shot engines from running poorly processed or unheated WVO/SVO, but biodiesel is not the same and we should make that clear. I haven't seen or heard of anything - other than possibly some minor hose change-outs - being necessary to run biodiesel. A friend of mine has run bio in her 04 Jetta for years. In the summer she runs B100 and in winter B20, I think. (She lives in a cold climate).