yes I've heard that before. And I've talked to some friends that are tranny rebuilders about that topic. and they tell me that staement is a scare tactic used by tranny shops that advertise fluid and filter change for a very low price to get you in to the door,and then when they open up your pan,
Gasp....look at all the metal shavings down in the oil pan oh theres something wrong internally we have to take the tranny apart and see what broke . and if you reply well lets just change the fluid for now .they reply we can't if we put new fluid in your tranny it will eat all the varnish off of the clutches and we will be resposible.and they then take your old fluid that was put into a clean catch pan before they started your oil change and put it back in and make you pay $20.00 or so dollors for there new gasket that they installed for you. So go ahead change your fluid and filter and remember this you can never go wrong doing somthing positive like changeing oil.and theres nothing coorsive about tranny fluid.