For info there is also a oil cooler/heat exchanger on the 3.0d - so worth checking that the coolant pipes for that are not blocked - causing the oil to overheat ?

https://www.realoem.com/bmw/enUS/sho...diagId=11_2328

Part 10 on the above - fed by a single entry/exit coolant pipe, exit/entry is the cylinder/head, oil entry and exit is via the cylinder/head directly.

If the noise is there from cold however, then I suspect it's the oil pump but also worth checking oil filter / bypass for blockages also.