Biodiesel has better lubricity than sulpher, thus it's the natural alternative. There's already many suppliers that mix in 2% biodiesel for their very low sulpher diesel fuel. What sucks is that when hurricane Katrina hit, the EPA suspended a huge number of standards including eleminating the mandate for ultra low sulpher diesel by January 2006. I've seen no word on when they are supposed to meet ULSD now, but hopefully it isn't pushed back more than just a couple months.