I am still running the BMW Genuine 5W-30 as it was recently changed just a few weeks before I bought the vehicle. I will look into a 0W-XX next winter. I was just asked in another thread what i thought of 0W-20's.

As for the degrading down argument, a well formulated true synthetic 0W-20 or 0W-30 does not need any Viscostiy Index Improver or Polymer so there is very little to shear down.

In fact in the Shear loss testing, it is normal to see neglible viscosity loss with two of the 0W-20's I have mentioned.

David