Is it useless to change the transmission fluid without cleaning out the torque converter first or at the same time?
Thanks!
No, its not useless.
BC.
If you are changing the fluid on a regular basis like every 25 - 35,000 miles, You are doing your transmission good. Not changing it at all is bad. Changing the rest of the fluid is good, but generally not needed.
If the transmission fluid is changed on a regular basis then dropping the pan, changing the filter and adding the proper amount of fluid is all that’s needed. The interval should be specified in your mom’s owners manual.
Whatever it says in the owners manual it is probably clearly screwy and you should ignore it. Have a local transmission shop drop the pan & change the filter every 3yr/30K miles. If this car has gone a really long time without a fluid change then have the pan dropped, filter changed, and then have a full fluid exchange done. Then just pick up the 30K miles filter change intervals.
Thanks!