We used 3 gallons of diesel season before last, 4 gallons this past season. I also use a diesel additive that I had to special order and get off road fuel from our club supplier. The only other alternative is the auto parts store where you can buy additive by the quart to treat the tank of your tractor trailer. That would be a lifetime supply for us.
As far as the gasoline motor guys? I was at our fuel dock during haul out this season, everyone was topping up with handfuls of $100 bills so I'm thinking that using fuel isn't an issue for them? We also only sell non-ethanol 89 octane.