I called bull on fuel additives for 12 years, then a 1999 7.3 with 340k on it made me eat my words
I have always lumped every diesel additive into the same bucket as those magnet things you clamp on your fuel line. Then a guy brought in a 1999 F-350 with the 7.3 and 340,000 miles on the original injectors, and he swore by one specific additive he had run since 80k. We pulled the injectors to chase a miss and I could not believe how clean the internals were, no varnish, no scoring, nothing like the black sludge I normally scrape out at that mileage. So now I am stuck in the middle: was this one truck just lucky, or have I been writing off something that actually does work? The other side of it is I have seen fellas dump additive in every tank and still smoke out the whole parking lot, so maybe it covers up a problem instead of fixing one. What convinced you one way or the other, and did you ever have a truck change your mind like this one did for me?