It's the same #2 diesel that is used by everything else. I don't think that you can even by high sulfur "Agriculture/Offroad" diesel anymore. They just have to by the "Red" non-road taxed stuff. It's a pretty hefty fine if you get caught running dyed fuel, especially in a commercial vehicle and they do check sometimes. In fact it is technically illegal to run your own homemade bio-fuels on public roads. The particulate levels are way down with cleaner diesel. I do think high sulfur diesel got a little more power out of the combustion.