I use Shell Rotella T in lots of our vehicles, especially diesels and motorcycles. They came out with a full synthetic recently, about $10 more per gallon; and, compared to the oil with a motorcycle manufacturer's label on it, it is still very economical. The motorcycles with a wet clutch cannot use car oil because of the additives. The new cars call for a 5W20 though so I can't use it there. Seems like it would be fine for a generator, diesel or gas.