Some of the truck stops have DEF nozzles that require a magnet to operate, so the truck drivers don't put it into their diesel tank. There are adapters you can

Some of the truck stops have DEF nozzles that require a magnet to operate, so the truck drivers don't put it into their diesel tank. There are adapters you can buy that will allow you to fill up your diesel-powered car or RV using the cheaper bulk pump.