Don't want to burn off road fuel in newer diesels cause of the low sulphur content. Gas stations were posting signs on pumps about a new lower sulphur content fuel a whille back. Older diesels actually run better on higher sulphur fuel the way i was always told. The DOT can pull anyone over (commercial or not, though unlikely if not). If they were to check your fuel you sure aint gonna save any money! My partner hauled cattle to sale one day in his old truck cause his other one was broke down and the one time he used that truck to go to the sale, you guessed it, we were burning off road fuel and guess who was at the loading chutes checking fuel?! DOT with a $1500 fine! You can buy off road (no road tax) gasoline at alot of places but I ain't tellin where