Transmission flush as part of regular maintenance? or scam?

90 Camry, YOU said “Firstly, what most people don’t realize it that you can only drain about half of the total volume of xmission fluid through the drain plug. Roughly, the other half is in the torque converter. The other issue is that transmissions don’t have filters like oil filters. They are correctly just screens.”

“The other issue is that transmissions don’t have filters like oil filters. They are correctly just screens.”

Not entirely true. SOME transmissions use screen filters. The transmission on the OP’s vehicle has a screen filter. I have posted a pic of the OP’s filter. With your post, are you trying to say to just not bother with the filter?? Not to address dropping the pan and doing something with the filter?? Are you saying to just flush it out?? That is not a proper service. Look at the picture of this screen filter. This filter can not be cleaned out completely enough to get EVERY particle of trash out of it. This is a $14 filter. Its less hassle to change it. Like I said before, never, EVER flush an automatic transmission without first dropping the pan and examining it for debris, changing the filter and reassembling.

transman

I respectfully disagree with 90 Camry and I might ask the following.

A flush machine may use the pump in the transmission to circulate the old fluid out and new fluid in via a diaphragm apparatus. Ten quarts of the old out, ten quarts of the new in and so on.

The pump in the transmission is going to be pulling the old fluid into the intake side of the filter/screen in the normal direction of flow so how is that going to rid the transmission of contaminants?

I also strongly disagree with your comment that low is better than an overage, within reason of course.
A quart over will hurt nothing but a quart down might, especially when considering fluid slosh due to acceleration and cornering.

When the owners manual mentions the word flush…I’ll do it. If it doesn’t, I’ll put it in the same category as refilling the tires with nitrogen.