Urban legend? I beg to differ. One of the challenges with reading discussion boards, which are full of great information, is discerning the quality of that information. Technicians, mechanics, and other experts or professionals in the business write in just about the same way as those who have never overhauled a transmission but who have a strong opinion. You have to figure out who to listen to. Why not check and see what various BMW techs (Weasel, killcrap), other professional techs (The Cleaner), and some others on this board with experience in the industry say?

An X5 Outpost thread worth reading on transmission fluid changes

Another X5 Outpost thread on transmission fluid changes

For the record, I don't think it is fair to say that transmissions will fail if you change the fluid. Obviously that is not true, as most don't fail. However, I think it is fair to say that changing the fluid increases the chance of transmission failure. A better poll question would be: "If your transmission failed, have you ever changed the fluid?" Instead, the poll focuses on fluid change practices, and includes all those who haven't had a failed transmission. For that reason, the poll has limited statistical value.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue