A friend and I have been making bio-diesel for about 4 years now. He has has an old diesel engine for as long as I remember. I'm not sure what it came out of. Probably from a tractor on his grandfathers farm. The question I have is there a problem using bio-diesel in a diesel engine that has no computer? He wants to restore the engine but doesn't know if bio-diesel would be right for it. Any info you guys would give on the subject would very much be appreciated.