Does the E53 take any special kind of Power Steering fluid?

[cn90]

Question for the gurus re Pentosin color...

Just sucked some of the old PS Fluid out (about 100 cc), it was Red Rusty color, similar to the color of standard Dexron-III fluid. Then filled with Pentosin CHF-11S, which is green (the PS cap says use CHF-11S).

The X5 was serviced by dealer over the last 9 years by P.O.

CHF-11S ($19.50 at Napa Auto Parts) has Green color.
From my reading on the web, apparently this Green color turns to Red after some miles? Is this true?

I am attaching a photo so you know what I am talking about...