So after doing all of my fluids in my X3 recently with the help of this thread, here is some additional info that may help others.....
1. For the transmission fill procedure using ISTA/D, it is best to do a dry run with the car BEOFRE you take everything apart. The procedure will not let you look ahead and there is no way to preview the entire procedure that I know of. The procedure does require you to prepare ahead for certain steps, and you have a narrow temperature window to get everything done. If the temperature goes out of the prescribed window, the procedure will not let you continue.
2. If possible, perform the transmission fill procedure when it is cold outside (i.e. fall or winter if possible). Even if you are very familiar with the procedure, as I recommended above, the temperature comes up pretty quick and it is really easy to blow past the required temperature window. Not that it can't be done when it is warm outside, but doing this procedure when the ambient temps in your garage are 85-90+ degrees could make getting the temperature timing more difficult.
3. For the transfer box oil change procedure, I could not find anything in the procedure that requires you to reset/recalibrate anything after the oil change. I did see a requirement for that for the previous model X3 (the E83) which I am assuming people are referring to. That said, ISTA does allow you to reset adaptations for the transfer box. Resetting adaptations is like clearing out historical data, so it doesn't usually hurt anything (I do it with my engine all of the time when changing tunes), so I went ahead and did it because I was in there - but I don't think it is required.
4. To get to the transmission oil fill procedure in ISTA was not very intuitive as the ISTA GUI is not very intuitive IMHO - it took me a while to find it inside ISTA after several internet searches came up short. Below is a screen shot of the tabs to get to it. It is after you have established a connection to your car. One note, when connecting to your car, make sure you connect w/running tests. There is an option to connect to the car without running the initial ECU tests, but if you do that, the procedures are greyed out for some reason and not available to run.
Vehicle Management -> Service Functions -> Power Train -> Transmission Control Unit 8HP -> Transmission Oil -> Oil Balancing -> ABL Transmission Control Unit: Oil Level Adjustment
