How to prevent wrong gas in diesel dually

Yes, and the move to pay at the pump options to the fuel islands makes this an easy process. If I were doing this I would also fuel at these islands or places like the RV islands at the fish hook.

 

There is probably a small concentration of gasoline a diesel engine would tolerate without hurting anything but I don't know what it would be. Auto diesel pumps are the same size nozzle as gasoline. Nowadays I think 1 ton pickups with diesel engines can use the larger truck nozzles but that wasn't always the case. I had to dremel out the filler neck on my 99 Powerstroke to get the high speed pumps to work.

 

The station attendant's at the turnpike service areas are really good at putting gas in diesel vehicles.