Diesel fuel is actually a light oil, and most oils will run in an older diesel. Many fleets, before the low sulfur diesel crap hit, actually filtered their used oil from the PMs and mixed it back in with the diesel fuel. before they started dying "off road" fuel red, a can of ATF every other fillup was considered a great injector cleaner. The only drawback to running it straight is thickness, in colder weather especially getting it to flow and pump well is a problem. Older diesels designed to run on high sulfur fuel, many owners dump 2 cycle oil in the tank to compensate for the lack of sulfur. Usually gets them a bit better mileage as well. About the only common fuel a diesel chokes on is gasoline, although a gallon or two mixed in a full tank of diesel was the old timer's "anti gel" solution before Power Service and others became readily available.