Goal for ATF drain and fills, when are you "satisfied?"

Joined
Aug 2, 2019
Messages
123
Location
South Central MN
In both of our cars, a full ~9 quarts replacement is basically a dealership task. Thanks, but, no thanks.
My local trusted shop will do a drain and fill for just over 3 quarts.
Both of these procedures are more than I care to do myself (at the moment) and require panel disassembly and other tools that I just don't have.
I can do a simple extract and refill through the dipstick in a few minutes for just under 2 quarts. I can do this a little more often in tandem with a PS extract and fill and have no mess and no leftover fluid for popping the hood once. That is cheaper and pretty satisfying. I will have the shop do the proper, more potent thing every couple of years, maybe longer as I drive less "these days."
 
Joined
Sep 30, 2013
Messages
13,534
Location
Indiana
If you know for certain you started with fresh, 50k drain and fills are reasonable intervals IMO.
 
Joined
Mar 31, 2019
Messages
261
Location
Minnesota
I drop the pan and change the filter first and then proceed with a line exchange. Mostly I only work on my own cars that are obtained with high mileage and likely at the end of and/or beyond the normal service interval. My latest doesn't have the normal pan/filter set-up so I drained and filled then did the line exchange. I like the thought of replacing all the fluid and a filter if possible.

I started just pan and filter but added the line exchange on my vehicles after learning it was fairly easy. Know your limits and where you can learn something and add to your preventative maintenance skills, do so. Don't risk disabling your car if you don't have a back-up plan like another car, a drain and fill is probably fine in many cars, though I'd recommend using the dipstick tube to vacuum the fluid out, drain plugs can cause problems and I usually drain the fluid as I drop the pan avoiding the drain plug use, slightly more messy...

And if you can run the motor for 1 minute 40 seconds while shifting gears, then repeat drain and fill. Just like the dropping the pan and line method your circulating the new fluid into the transmission and hopefully draining out mostly old fluid out a second, third and maybe even a forth time for about 12 to 16 quarts depending on how much volume is drained each time. I'd think doing it in immediate secession rather than mixing in for a longer time period likely gets more clean fluid volume in use. Your result may vary. I think of the transmission as a hydraulic machine and it might have similarities to changing the fluid on a hydraulic jack, for example.
 
Joined
Sep 9, 2020
Messages
564
Location
Scottsdale, AZ
When I buy a car used I just do 3 drain and fills over the next month (one every weekend) to get a clean baseline and know the mileage/use on almost all the fluid is. Then repeat every 30,000 miles or 15k on my truck if I’m towing a lot. Throwing away plenty of good fluid I’m sure but at $17 a gallon who cares?
 
Joined
Jul 11, 2021
Messages
940
Location
Close to Sierra mountains
does not drain the converter
I only talked about the pan fluid and the filter nothing else with my service. Besides rarely does anything accumulate in a torque converter because the fluid is not only constantly flowing under pressure but you also have centrifugal forces applied. When I decide to have a custom torque converter made the first thing I do is cut and split a stock converter to see how it is designed. Most are almost the same but there are exceptions.
But I can't say as I ever remember seeing anything except what ever the last fluid was in any of them?

But seems you mention the torque converter why doing a proper complete fluid replacement using a service machine to do the service should be done and as a service at least at or before 75kmiles.
 
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