Change the fluid as preventive maintenance.
One or two posters of the X5 forum do long daily drives and now show 200K+ mileage with the original trans and fluid. The rest of us do not have that type of driving patterns. I think everyone recognizes that trans wear occurs on shifts not hi gear runs down the hwy. A fluid and filter change is a good thing.

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2005 X5 4.8IS
The Blue ones are always FASTER....

Current Garage:
2005 X5 4.8is
2002 M5 TiSilver
2003 525iT
1998 528i
Former Garage Stable Highlights
2004 325XiT Sport
1973 De Tomaso Pantera, L Model
1970 Dodge Challenger T/A 4 sp Alpine White
1970 Dodge Challenger T/A 4 sp GoManGo Green
1971 Dart Sport, “Dart Light” package
1969 Road Runner 383
1968 Ply Barracuda 340S FB Sea-foam Green