Diff Problems?

[Fed]

Has anyone had Diff problems with their Z4M? I have a 2006, that I bought new, and has been babied since purchased, no clutch drops, burnouts, track time. at 40K miles started hearing a metalic grinding/humming when driving that got louder as the car sped up. Took it to the dealer who said it was brake noise and normal on the car. Took it to another dealer who drained the diff fluid and found metal in it, and replaced it under warranty.
I'm trying to find out if this is a common issue on these cars? I'm still dealing with BMW to fix my squealing brakes which they also tell me is normal.

[hansaysso]

how often did you change out the diff/tranny fluid? bmw tells you that their diff/tranny fluid doesn't need to be changed out after the 1.2k mile break in service but thats a joke.

[DarkstarZero]

You should replace your break pads with something different anyways. You can get really good street pads that are better than the OEM ones, don't produce break dust, and don't squeel for around $100. They're not hard to replace on your own either.

[trsbmw]

Originally Posted by hansaysso

how often did you change out the diff/tranny fluid? bmw tells you that their diff/tranny fluid doesn't need to be changed out after the 1.2k mile break in service but thats a joke.

This is incorrect. BMW service schedule for diff fluid (and transmission fluid, for that matter) change is at every Inspection II. (which should be about every 55-60k according to the Service Interval Indicator)

I myself think it should be sooner.. (I plan to change at 15k and have a used oil analysis performed to confirm status of the old oil)