As far as removing all of the fluid from the trans, many places offer a power flush. They actually hook a machine to the trans cooling lines and while the old fluid is pumping to the machine, new fluid is being replaced. I do recommend this if it is done at regular mileage intervals. However, if you're past due, replacing the filter is a better idea.
If you only do a pan service (and only loose the fluid from the pan), start with around 3 quarts and go from there. Remember, the level is checked when at operating temp.
I hope this helps. Let me know if you have any other questions.
Positive feedback is appreciated.
Wednesday, March 17th, 2021 AT 3:49 PM