I have two yellow John Deere diesel jerry cans that contain fuel that’s at least ten years old. The cans have the old style nozzle and vent arrangement which I much prefer, so I’d like to bring them back into service. My concern is that they’ve been sitting for so long, there’s bound to be a bunch of nasty in there. Are there best methods for cleaning them? I can dispose of the old stuff, but then what? Thanks for your thoughts.