I completed flushing my transmission oil last Saturday.
1. first, make sure the car is on level ground, (1 ramp on each tire).
2. I removed the oil level plug, drained around 1qt then plugged it back in.
3. I removed the drain plug, another 2 qts came out and then plugged it back in.
4. I then removed the 20 bolts to remove the pan and gasket, another 1 1/8 qts came out.
5. I removed the filter and replaced it with the wix on and cleaned the pan and the 4 magnets in the pan, there's a bunch of grease like fine metals. it's very important to remove those.
6. reinstalled the pan with a new bolt (old one was rusted enough that it's starting to break when loosening it, broke 2 bolts while removing it.
7. disconnected the transmission hose from the upper part of the radiator and filled with 4 1/8 qts of atf thru the radiator using an oil pump. (easy peasy this way).
8. connected another hose to the end of the hose and towards an empty container on the floor with a mark for each quart of oil. (used an empty wiper fluid container).
9. started the car until it filled up to at least 2 quarts and stopped the engine.
10. refilled another 2 quarts of oil then repeat item# 9 until you get a reddish color atf. (I used at least 14qts of oil)
11. put back the hose to the radiator and you are done with your flush.
12. all in all, my old atf oil has been used for 70000 miles and it still reddish in color but a bit darker. it seems like I could go another 30000 miles with the old one.
Here's the youtube link how simple it is to flush it.
https://youtu.be/Q3fu0wiabFQ