I am helping a friend install a Buderus Oil fired boiler. Just about done. We need to test it and he never called the oil company for a delivery. Now with the cold wave, they cannot come for a week. Anyhoo, I suggested that we test it with off road diesel fuel to at least make sure every thing works. He seemed nervous about that, but I remember reading there is no difference between off road diesel and heating oil. Is that true?