Did a search but came up with nothing, maybe the way I wrote it. Got some old diesel fuel in my MH. Last time we used it was 2015. Some time after that I put about 20 gals in it and now it has about ...
I'd use the fuel, but I'd pour a bottle of Seafoam in first, and I'd carry a new fuel filter in the unlikely event that there is algae in the tank. I'd fill up asap at the nearest station too.
BTW, there's typically an infrastructure to deal with contaminated diesel fuel in big rigs in most towns large enough for a diesel repair shop so if something does happen...