Just read this notice on this web page (about 2/3 of the way down) that warns against flushing an older high-mileage tranny. (Mine has 111,000 miles and has never been serviced.)

To Flush or Not to Flush?

Flushing out the old ATF and replacing it with new fluid can prolong the life of a transmission, provided the fluid is changed fairly regularly, say every 30,000 to 50,000 miles. But if the transmission on a high milege vehicle (say over 100,000 miles) has neer been flushed, it's probably best to NOT flush the fluid. Here's why: The detergents in new ATF may loosen up accumulated crud inside the transmission, which could cause some problems within a few thousand miles or so after the flush. So if your fluid has never been changed and your vehicle has a lot of miles on it, it is probably best to just leave the fluid alone and top off the fluid level as needed if it is low.
Any thoughts??
Ed