X5 4.4 - Sludge in engine and oil filter housing... help!

[sunny5280]

Originally Posted by Penguin

Well, I probably should just drop this, but why is that any more of an "Urban Legend" than the "Urban Legend" that changing your AFT will make your transmission last longer?

Arguments pro "change the ATF":

• BMW recommends it at 100K mile intervals.
• No fluid is lifetime. Lifetime being defined as never change.
• Fluids act as a detergent and become dirty with use.
• The protective qualities of lubricants breaks down over time.
• Every other fluid in the vehicle is subject to change at regular intervals.
• Other vehicle manufacturers recommend ATF changes.

Arguments con "change the ATF":

• In 2002 Mike Miller, head technical editor of BMWCCA, made the recommendation to avoid ATF changes due to his observed increase in subsequent transmission failures.
• Numerous web sites making the same recommendation as Mr. Miller.

So we have facts for pro "change the ATF" (I put this in quotes because my argument has never been to change the ATF but more it doesn't hurt to do it) and opinions on the con "change the ATF".

In 2009 Mr.Miller appears to have reevaluated his 2002 recommendation and no longer has the passion for it he once had (but does continue to say there is a risk). As for the numerous web sites I suspect they picked up on Mr. Millers 2002 recommendation and ran with it. And now discussions on this subject make references to one another (it happened in this one) in a form of circular support (I've seen this happen too many times).

Many disagree with my urban legend label but that's how I view it. An unsupported claim has been made and repeated ad infinitum and taken on a life of its own. So much so that people making it feel threatened when someone dare question it.