A little story on industrial Diesel fuel. Here in Los Angeles is the Hyperion sewage pumping plant that for years used Worthington dual fuel engines (16" bore x 20" stroke) running at 360rpm to both generate power and to provide the compressed air for pumping air through the sewage to hasten the break down of molecules (the engines are not used anymore because of emissions). The engines used 10% Diesel and 90% methane created by the sewage being warmed to 140 degrees and pressurized to 5 pounds in huge register tanks. During the 70's, one of the employees had a Mercedes 240 Diesel that got the bright idea to just "borrow" some of the #3 Diesel. After a couple of tanks, he burned holes in the top of all of his pistons since it is a hotter burning fuel. #4 as you described is even hotter. You can run the fuel in your bus, but you should reduce the injector size down at least one, if not two sizes. Personally think it is not worth the risk for a blown engine to run it. Good Luck, TomC