The service manager is partially correct, Ford did recommend switching some transmissions over to Mercon V to help with torque convertor shudders, however this does NOT include the Superdutys. I did a lot of searching on this topic a few months ago and the concusses seemed to be that Mercon V is not good for this model transmission. Do a search on this forum, if I remember correctly someone else had the same problem with a dealer. When he confronted them they towed it back to the dealer and changed the fluid back to Mercon.