From another thread: What exactly are those obstacles for a modern diesel engine? Older diesels don't have a problem running bio-fuels. Manufacturers had limits stated for amounts of biodiesel, but that most surely CYA print. It is relatively easy, and likely the only source, to get homebrew fuel which may not meet accepted standards. They didn't want to pay for repairs caused by unknown adulterants in the fuel. There may be interaction issues between biodiesel and the motor oil formulated for diesel in mind back then. Which may still apply, if so. Biodiesel is already ultra low sulfur, so that isn't an issue. Are modern diesels so complex they can't adapt to different fuels? Is this fixable on current engines with some mechanical and programming changes, like FFV gas engines? Or would they need to be redesigned from the ground up?