Ford Repair: Dont change the AT fluid?, transmission failure, filter replacement

Question
I was told not to change the AT fluid in a 91 Escort w./ 65k mi. as it has never been serviced before and replacing the fluid will cause the trans. to go if I replace the fluid now? Ever hear of this or should I go ahead and do a fluid & filter replacement? Thank you.

Answer
Randall-

  This is always a tough one.  You've got a 50/50 chance that you'll encounter problems.  What happens is, as the fluid breaks down with mileage, friction increases on bands and seals.  This can cause leaks which would otherwise lead to transmission failure, but the old fluid starts to build up a varnish around these areas which effectively plug the leaks (if they're there to begin with).  Since transmission fluid contains detergents, when you add new fluid, it strips this varnish away which can open up any leaks and cause problems up to and including transmission failure.  Now, you're transmission may not have any of these leaks or any wear in which case a fluid change would be a good thing.  However, if they are there then you could be looking at some potential problems.  I usually tell people to go ahead and change the fluid since, if it's left in, it's going to mean a transmission failure somewhere down the line and if there's problems you can get them out of the way now.  If that's the way you go, I'd start with just a change of the fluid in the pan an the filter and see how things go.  It's really up to you, but there's really no way to tell if there's any problems unless you actually change the fluid.  Hope his helps.

Steve