I have a 1999 F 350 7.4 diesel with a ZF 6 speed , when I bought the truck it shifted hard and would grind 3rd 4th and 5th or downshifting unless granny shifted. so I changed fluids with amsiol synthetic and it shifted better but grinded worse, On advise of a Transmission mechanic I added some limited slip additive to the tranny and that made it worse (grinding ) I havs since drained and refilled with a synthetic blend and it seemed a little better but not alot, still grinds if you try to shift normal. Anuther friend (Mechanic) reccomended to try BG syncroshift. But that stuff is expensive, about 2x the price of any others.
Its also a little thicker than anything else ive tried. The tranny makes absolutly no noise and seems tight. Other than the shifting problem I would say the tranny is OK.
Has any one ever tried the BG stuff in their truck? or does any one have an opinion?
Other than a rebuild. Or do you think that is the only option.
I used to be a Mechanic Years ago but never built a standard tranny, only ever worked on the older automatics. But there is always a first time for anything, any advise is welcomed.
Chuck.