Been using B50 (cotton seed oil) for three months with no problems. Just runs better with it than it did on diesel. Seems to be quieter, smoother, a little more responsive and my mileage has not changed except that I think it increased a little. The one thing you need to do is change your fuel filter a few times earlier than you have, bio will clean your fuel system. Took two changes to finally get it flushed out.