Trans fluid Drain & Fill - opinions needed

[Crispy]

2018 TX w/ 78k. I did a 6 qt. trans Drain&Fill at ~30k so I know the drill. My question now is if I do a 3 qt. D&F, can I leave the car on the jackstands and do a second? If I run through the gears for a couple minutes on the jackstands rather than driving the car, will the new fluid be mixed enough with the old for me to do another D&F? What you think? Thanks, C

 

[Crispy]

Well.... not quite the response I was hoping for so I went ahead without your opinions. First I drove the car up to operating temp and then brought it in and put it on four jackstands. I leveled the car under the rocker with a 4-foot level. The first drain removed about 2.5 quarts of pretty dark fluid. Put 3 quarts of Idemitsu TLS-LV in and ran through the gears, shifting all the way up to 8th. I went back to Park, Reverse and through the gears to 8th (~65mph) a couple times for a total time of about 5-8 minutes. I drained that to see much more red fliud but still dark. Put in three more quarts and adjusted the level to a dribble. The last bit I got out was even more red and looked to be a big improvement using color as a guide.
It was definitely easier not to drive the car between the two D&F's. I think it worked fine. C.

 

[garbageguy]

Thanks for updating with your recent experience. I would be concerned about running-up to 8th gear under no load. But it does seem like you got more old tranny fluid out using your idea.

 

[Crispy]

I don’t think I got more out because each drain was the same at just under 3 qts. I thought the goal was to mix the old and new throughly so that’s why I wanted to run the car, in this case on jack stands. I just wasn’t sure how long it takes to get fluid pumped through the system and mixed. I know the torque converter holds a lot. It was so easy, I may do another 3 qt. drain&fill and call it good for another 50-60,000 miles. C.