I have never changed the fluid in diff or transfer case. Once around 180,000 or so I drain and refilled the transmission fluid. I currently have 241,000. Maybe lifetime really means life time. I have been think about changing the transmission fluid and filter because of all the talk we have had about fluids but I am not sure. Like waynesworld said he changed his fluid and the diff crap out 2 days latter. I really don't want that.

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2010 X5M /// R63 AMG...Wifey's 540HP Family Hualer

2001 X5 3.0i Sport 335,448 miles & counting...
SMG M3 Steering wheel
E46 Stainless Racing Headers
4.6is Exhaust
Turner Pulleys
Afe Intake
Brembo drilled rotors
PowerFlex Bushings
Hualingan
30mm H&R Spacers rear
20mm H&R Spacers front
Bavarian Autosport High-Performance Coils
Active Autowerke's Performance Software