The actual issue is the material BMW engineers chose for the long plastic timing chain guides. Over time and at about the mileage the OP currently has reports have been pouring in that the plastic guides are disintegrating which allows plastic crumbs and debris to be caught by the screen over the oil pump pickup. The oil pickup screen soon gets completely blocked which then starves the engine for oil and the engine fails.
BMW is putting a lot of folks in a tough spot looking at a $25,000 repair bill on a 5 or 6 year old car. We've also had reports here from owners of 5 or 6 year old 550i's with seized engines and a quote of $40K to replace. Many of these decide their best option is to part the car out.