I changed the fluid and filter every 60-70 K miles. It's not that difficult. I now have 220K miles and never an issue with the tranny. Although, did you know that if your MAF is disconnected your tranny acts up ? I found out by mistake. ONE important thing; don't over tighten the fill/drain bolts.

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X5 3.0 AUTO -2001 - 238,000 miles