Why are you using 60wt oil? That's not needed or recommended. Valvoline is not on the BMW LL01 approved oils list. Escpescially that weight. why are you gonna dump money into the bearings when that might not be the cause. Just because it has 357,000 miles doesn't mean it's the bearings going. The knock could be a few things, includig the oil your using, or something simple like bad gas or clogged cats.