I switched out the OE fluid at 100k miles, went with Mobil1 75w-90 syn.

No issues in the 80k miles after change, even with severe duty (towing 6000 lb trailers in temps exceeding 100 deg F).

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'03 X5 4.4 Sport, last of the M62s (8-03 build date)
I believe in deadication to craftmanship in a world of mediocrity!