High mileage tranny, 414k, slipping when first started.
 

Car has 414k miles. Bought the car at 230k so I put roughly 190k on the car. I believe the transmission is original but can't be 100% sure. It is slipping when first started up then it does not happen after warming up. Changed the transmission filter and fluid but same symptoms. Car runs good otherwise. Something sinister or just high mileage? How many miles can be expected from a Mbz transmission? I have a spare ( unknown condition ) transmission but don't want to swap it out unless I had to. Any collective wisdoms?

Step #1: Tell us what engine model, and what transmission model.

Had to rebuild the transmission on my 300SE at 90K miles five years ago, first started to slip and then getting in reverse would get harder and took longer to engage. 2nd gear and reverse shattered on a trip to San Francisco, still made it to SF and back to LA.

Count how long it takes for the car to go backwards after you put it in reserve, should not take longer than 2.5 seconds if you have a healthy transmission.

Getting 414k on an original transmission is pretty good, I would think.

My bad. It is a 1987 300D 722.317 transmission. I drove it today and the transmission was perfect.