I thought it was time to have the trans fluid (and filter?) changed in the '13 Sierra, that has 91k on it.
The service writer said: "the flush machine cleans the filter, it's a pressurized system."
Just wanted to check with those who are more up to speed than my 1980's experience.
I've heard the pros and cons from a lot of experienced folks, and there probably is no right answer. The thing that I key in on is that IF you have a relatively clean transmission where the fluid is slightly darker in color and not totally contaminated, then it can make sense to get the power flush done. On the other hand, if the transmission is already causing some problems, or has very dirty and smelly fluid, then it's not a good idea.
From what I was told, in a very dirty transmission, the power flush will loosen caked on chunks of material that can potentially get stuck in the tiny valve body orifices and screens -- thereby creating a problem, or making an existing problem much worse.
Therefore I usually stay away from the power flush on cars that have high mileage and never had any regular scheduled transmission maintenance. At that point it's a crap shoot. OTOH, if the transmission has been serviced regularly and is in good working order, then I see no reason not to get the power flush done.
The filter aspect is probably bogus -- a new filter is always better than backflushing a used one -- especially at 91K miles
Just my $.02