if not the merc then how about a late-ish vw TDI? they should be ok... only thing is i'm not too sure how computerised the injection pumps are and the what intolerance this gives towards the fuel....
yea, there seems to be alot of conflicting and "i think you can use fuel xxx with engine y" posts

Good vw forum (american!) with a whole biofuels forum http://forums.tdiclu...isplay.php?f=52
