Biodiesel uses treated veg,soy ,cooking oil etc. Treated as removal of glycerien, proper ph level etc. I know a fuel distributer licenced to blend biodiesel. They watch thier bio oil source carefully. I trust their biodiesel and run it in my truck. the main advantage of bio is not low cost source oil but a oil molecule containing aprox 40 percent more easily released oxygen. This burns the petrol diesel more completely usualy resulting in slight power increase less soot-more complete burn and slight increased milage. Untreated veg oil especially for deep fryers is bad increased acidity is detremantial to fuel system parts burning oil containing glycerien is completely WRONG. also be aware rubber hoses could be effected-swelling choking inside diameter. Gary