I thought the 'flush' done by a fluid exchanger was bad on high mileage transmissions due to the possibility of getting clutch debris stuck in pump or valve body that would cause issues. I've not heard of that being the case by just doing drain and fills (where you have no forced fluid through the transmission).
Replace transmission fluid or no? (4 Viewers)
- Thread starter nagrom46
- Start date
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I would never due to pressurized "flush" on a machine. It's not hard to DIY a full exchange at home. I do one every 30-45K by dropping the pan, cleaning the pan and magnets (it will be full of crud), replacing the screen/filter (after all, a new one comes with the pan gasket), topping it off, then using the transmission pump to expel ~2 quarts at a time, and adding ~2 more quarts at a time back in via the cooler lines until clean fluid comes out (this takes about 4 gallons of fluid). This will 1) get all of the gunk out of the transmission, 2) avoid using pressurized fluid that may put contaminants in areas you don't want them, 3) get you all new (i.e., non-mixed) fluid, and 4) allow you to verify the transmission level at the very end. Using a Motive Power Fill makes the job quite easy, but I've done it in the past with a funnel (it just takes 3X longer).
This approach has many benefits over a drain-and-fill, including 1) all the fluid is replaced and only nominal contamination remains and 2) saves time in the level check (you only do it once, as opposed to checking the fluid level at every drain and fill). If you aren't checking the fluid level at a drain and fill you definitely should be. It's like checking the oil level via the dipstick after an oil change - I'd never complete an oil change without doing that - so I don't complete transmission services without doing it either.
