I have always heard that if a tranny is not maintained on a regular basis, then it creates more problems when fluid is changed. If it necessary, be sure it is thoroughly flushed, and not simply changed. Do a google and you will see tons of info on this subject. Best to change the fluid and filter at least every thirty k during the life of the car...we are talking auto tranny...
What you say could be entirely true. (Caveat: a single experience is just that)
My folks have a 2000 Toyota Avalon. Just to show how little they drive it, it has 35K mi on it. I suspect they have never changed the tranny fluid. Auto, of course.
An engine light came on, and we had it scanned at the local dlr. Scan came back “tranny shifter solenoid”. OK, so Toyota has a very logical 3-step process for diagnosing/fixing this. Nobody expects a tranny to go bad at 35K.
1: You just flush the tranny, hoping that a piece of gunk is interfering with the shifting. (They are aged 90 & 91, I am doing all the driving now, and before/after the light came on, I detected no difference in performance) About $300-$400. Light returned after about 3 days post service.
2: You replace the solenoids. Obviously this involves far more serious work, dropping the pan, getting in there, etc; About $700. Light returned after about 3 days post service.
3: Replace the tranny. About $2800. Ugh.
We’ve completed steps 1 and 2. What I have NOT done is to reset the warning light, because a fault only has to occur ONCE and the light will latch on, permanently. This can be done away from the dealer by disconnecting the battery for 15 mins or so.
Not eager to proceed to step #3 as you might imagine.