And the oil wars begin again....
You will find two main camps. One follows the BMW CBS (about 15,000 miles or a bit less). The other splits it in half (7,500).
The first camp maintains that BMW knows what they are doing and points out that oil related failures are not occurring.
The second camp maintains that BMW is pushing the envelope too far to cut costs, and that oil related failures won't show up until the cars start to get high mileage. The VW/Audi 1.8T sludge debacle did not become apparent until the engine had been in service for 7 years, to show one example.
A third small camp does very frequent changes in the belief that the N54 is exceptionally hard on oil. There is very little hard data to support any of these camps, since in spite of all the noise very few are posting oil analysis results.
Whatever you do, use oil with BMW LL01 approval. For practical purposes that means oil from the dealer, Castrol Syntec 0W-30 or Mobil 1 0W-40. The European approach to oils is different that your father's Buick, and for us what matters is the BMW LL01 specification. The quack lube places won't have it.