First a little background: Yesterday I completed the transmission service on my wife's car (133K miles, second trans service in the car's life) and the week before I completed it on mine (66K miles, first transmission service).

I did the basic trans pan drop/clean, filter change, and refill.

Both cars had nearly identical amount of ferrous debris caught on the pan magnet. It wasn't much, just a thin film of "schmutz." The filters were clean as a whistle.

This all seems like a lot of fuss and bother.

Now that I have the proper tools (scan tool that reads trans fluid temp, CTA fill adapter, CTA pressurized fluid fill station), why not just pop off the drain plug at every 10K mile service interval and "overfill" a couple of liters of fresh fluid, let it come up to temp and then drain off the excess?

Very little bother (other than idling until the trans temps come up), and seems to accomplish a similar goal.

The only downside I can think of would not being able to visually inspect the filter and magnet for signs of major problems and an additional ~$35 in fluid per annum.

 

Tranny services are so infrequent yet so important, I'd rather just do it right. You do want to clean out the pan when doing changes.

My dealership lets me bring my own parts and just pay for labor. Sometimes you just don't feel like climbing under the car.

 

The nearest dealership service department are absolute thieves and hacks. In fact I've had a very hard time finding any shop near me I trust. So climb under the cars I must.