To do a complete change of oil in the transmission, you will need whatever your system holds in total and add two quarts to this. Get a new filter. Use Sealed Power with the ID marks on the filter as SPX, microfelt or filtran or the Allomatic with a large "F" on top of the filter. Do not use any other as these two are the best and were at different times oem filters. After changing the filter and pan gasket, add 6 quarts to the system and disconnect the top line at the transmission. Use a large container to catch the trans oil in and be able to see the fluid coming out of the line once the engine has started. Have the rest of the containers opened ready to add. Have someone start the motor and you start adding fluid as fast as possible. Stop adding oil at the last two quarts, and watch the oil going into the container. When you see the new oil starting to go out of the transmission line, stop the engine immediately, and re-attach the transmission line and re-start the engine and check the oil level and add what is needed. It will in most cases take most all of the oil. Now you have done a 98% -99% complete transmission oil change. From what I have heard over the years about the shops having transmission flushed is nothing but nightmares. 2 to 4 weeks later and you need a transmission. This is much cheaper and you will not hurt the transmission here. For non-synthetics, Mobil, AC Delco, Aamco (Mobil repackaged) and Chevron Delo. For synthetics, regular Amsoil and Redline are the two best. If you have something that works for you and have had no problems with it, then use it.