Hello all, first post. This may have been discussed before, but I couldn’t find it. My 1996 has high miles and is started to shift hard so I wanted to change the transmission fluid. Ford manual states Mercon and I have read on here they some have better luck with engine oil. I went to auto parts store and the guy there stated I had the wrong fluid and said my truck required Synchromsh. Is this correct? I don’t see this fluid mentioned anywhere. Thanks!