In the not too distant past diesel owners raced to perfect the perfect bio fuels. Understanding what is, and what is not good for a diesel fuel system can’t be identified until a failure occurs. Like this one, individual took soy based vegatable oil and filtered it. Adding no substantial chemicals, not cut with regular diesel fuel, just filtered soy veggy oil. There was a moment when the truck seemed to run off of this concoction, but soon after the truck sat for a few weeks, the soy began to gel. Taking up residence in the fuel tanks, filters and housing was a tar based material settling in a thick black film 1/4 deep. A brave technician used his natural flavor detection system to identify this substance as SOY!