Diesel runs on compression to create combustion. Gas runs on combustion to create compression. So gassers create spark to create a controlled explosion. This to me would pose a greater risk. That said I'd be more worried about the fridge on LP catching gas vapors and igniting than the engine. That's an open flame. I always turn mine off. Not only won't the gauge register unless I turn it off and back on, it's rather obnoxious and inconsiderate running your engine blowing exhaust around the rest of the folks getting fuel. All my vehicles are gas though. I almost always see OTR trucks letting them run for fuel, eating sleeping etc. Seems OTR drivers never shut down their rigs.
