I had an '85 F250 with over 275,000 miles on the original motor and injectors, etc. One clutch though After the diesel fuel changed back in ~'02 my injection pump would drag horribly during start ups, especially on cooler fall and winter days. Plugging in my block heater had no effect. After replacing various fuel system components and different small town Ford dealers telling me to replace various injection parts of system, I wasn't going to replace every part of the system. I was going to college at University of Idaho at the time. I went home one Thanksgiving and took my pickup to a larger Ford dealership. This dealership had seen of number of the pickups and even though the pickup was almost twenty years old at the time they called me the next morning to tell me what was wrong with the pickup.

Newer fuels had been given less and less additives, often filtering the fuel further and actually contained fewer lubricating properties. That makes diesel less "slick," at least this is how I understand it. This is done to help meet emission standards becoming stricter and stricter, thanks primarily to the great EPA. Thank you to the government bureaucrats!

Back to my point of the story, the dealership told me to pour an entire quart of AFT into the pickup every other tank of diesel fuel. I could run a quart every tank if desired, but that was not a necessary part for the smooth running of my diesel.

I had to sell the pickup a few years later. It was still a strong running motor that gave me no problems. I had to sell the pickup because I lost use of my right arm due to a motorcycle wreck.

I still miss my '85 with nearly 300,000 original miles.