Never had anyone from MB tell me to use ATF in the fuel, however just after I bought my first powr stroke diesel I ran into a guy at the service station, talked about the truck and he said before he left to run a little ATF through it every so often, he owned a diesel repair shop and had no reason to blow smoke so I feel he knew what he was saying. Had the name on his truck, but did not offer a card so he wasn't looking for buisness. That particular truck is with the ex and has over 100K and still purrs, however not as good as mine.