I'm about to do an ATF change on my (new to me) 169k mile 2001 x5 3.0i. I've spent hours reading things on the site, trying to make this as successful as I can, but I have a few questions still:
Based on what I'm learning about the car and the maintenance, the PO was more into repairing things when they break than in preventing anything. He gave me all the receipts since 2004/46k miles, including $12k+ of repairs in the last two years. So I'm assuming the ATF is original.
I will be using Castrol Dexron VI, certified ... I have the Bentley manual and will be using that as my main instructions, with info from the site here to fill in some blanks.

Does it make sense, as a precaution, to try to check the ATF level under the same conditions (idling in Park, car level, at 30C) BEFORE doing the change? Anyone ever done that? That way, measuring what came out vs. what goes in would be more meaningful.

Wanting to get as much old ATF out, but without doing anything with the engine running, I'm considering also disconnecting the ATF cooler lines at the radiator (only with the engine off) - even if it only gets another quart out, it seems easy to do. Comments?

For the step that includes shifting through all the gears after the initial cold fill, I figured I'd test how that works, and did so earlier today. Car idling, foot on the brake, I shift into Steptronic mode and shift into 1, then 2 (no problems so far), then 3, and the display shows it go to 3 but then back to 2 a second or so later. I don't know if any shift actually occurred. Same thing with 4 and 5. I can shift the manual lever so it shows 3 then 4 then 5 on the display, but it takes itself back to 2 within a second or so and I can't tell if any shifting actually occurred. Is this normal? Did shifting to the higher gears actually occur? Will this phantom (if I'm right in thinking that nothing actually shifted) shifting be sufficient for the ATF change procedure? Am I right that this cycling through the gears happens with the parking brake on, and my foot on the brake?

It would not be hard for me to do all of the above, take a spin around the block, where I actually do shift into all gears, and then check the level again.

And in case it helps anyone else, while changing the diff oil over the weekend, I determined that the ATF drain bolt is a Torx T40. I cracked that and the fill bolt loose and then tight again to make sure I won't have any problems there.

Thanks.