I fix gas pumps for a living and ever since ultra low sulfur arrived we have been seeing issues getting worse and worse. I was told several years ago the way they get the sulfur out is mix the fuel with sea water (salt water)! Todays diesel will ingest or hold up to 30 percent water. Years ago when we would pull motors out of the tanks, we would hold on to the 1-1/2 black pipe for dear life because it was so slippery . Today we hold on for dear life so we don't have to go to the emergency room because our hands are full of rust. Anyone who has a steel tank should be very careful, the metal is severely rusting , its just a matter of time. The microbs and humbugs are coming from your delivery company. They get it from the distribution centers. If you have the smallest amount of water in your tank , get it out asap! Keeping your tank as full as possible all the time helps alot . RUN ADDITIVE ALL TIME! i will post some pictures. Additive is needed regardless if its new or old engines. USA has terrible fuel compared to the rest of the world.