Resurrecting an old thread. I just did this on a 2006 330xi 6 Speed (no active steering)
No issues with old fluid, but the power steering pump is operating much quieter. An extra tip: you can prevent the clips from falling down by using some duct tape until you’re ready removing the power steering tubes from the reservoir or installing a new reservoir. Removing the filter in the old reservoir was key to removing all the old fluid. Also, I used a few strips of duct tape to hold the power steering lines in place against filter box. I had 0 fluid drips and and no issues with air getting trapped in the system. Given I only had 2 bottles of CHF 11s, I used about 1.5 to make sure I had enough for a top off after letting the car idle and turning the wheel back and forth. Be very careful about your brake booster lines! You can rest your arms for support on the cowl/fender/filterbox.
Here’s some NSFW power steering fluid. Apparently receipts show it was changed a few years ago. This looks original. Makes you think what some mechanics are up to.
View post on imgur.com