Transmission question

[drfred]

My two bmws are fine but the expedition with 190k miles has been slow to shift the last couple of days. I looked in the driveway this evening and I have a pool of reddish fluid and the dip stick is down a little. Maintaining the level is no big deal by just adding fluid. I recall a conversation with a service advisor who said that he would not want to drain and change the fluid with this many miles because he was afraid of what sludge might be dislodged
when the procedure is done. At that time, there was no leak I was just asking about changing the fluid. Any advice would be appreciated as usual.
Thanks,
Fred