Originally Posted by
Stratosurfer
Jeep,
Type in Used Motor as Diesel Fuel in Google and you will find volumes. I think the 7.3 IH and Powerstrokers have been doing more of this because they apparently don't have an optical sensor. The U.S. Military (you'll find many sites on this) spec out all waste oil from their fleet vehicles to be filtered and put in the fuel tank, this has been going on for probably 50 years or more and just recently been codified as mandatory in the military.
Filtration is the key, and ensuring no water/antifreeze in the WMO.
I have a friend who was Chief Technical (Combustion) Engineer for Conoco Phillips and was with them for 40 years. He says the ideal oil to burn would be SAE 10W w/no additives. Tranny oil's Friction Modifiers are colloidal metal and when burned can leave metallic deposits. Motor oil has some colloidal metals as additives as well, but not nearly as much as ATF, he advised strongly about not using ATF. He said 10w mineral oil (read no additives) would be the most ideal fuel stretcher for any compression ignition engine. The IP will love it, the lift pump shouldn't have to struggle too hard to move it particularly if blended w/ULSD and it should burn very clean. I am going to focus on a source of WMO that is from gas vehicles only as most are moving toward 0W-30 SAE oil and at the same time see if I can source some bulk 10W mineral oil in bulk. If I can get 10W mineral oil in bulk at around $2.00 gallon, taking into account that it requires no processing, I would think this would be a nearly ideal fuel for our 6.5's.