[Biturbos4] All causes to turbo failures known?

[Brad R]

When one of my turbo's went bad a few months ago, the dealer stated the
cause was that the inner oil seal went.  What would you think would cause
this?  I know the car has had Mobil 1 oil changes every 3-5000 miles.
Unfortunately, I have only had the car for about 15k out of the 68k on it.
I let it warm up and cool down, but I am not sure if they previous owner
did.

Audi did put in upgraded K03's.  I guess I am just looking for ways to
prevent that from happening again.

Brad