BMW says Castrol TWS 10w-60 is the only oil you should use for the S54, anywhere, any time, period, end of story, finito, no more questions. Otherwise the engine might fail. Seriously.
Actually IIRC there might be like 2 other oils they allow but they are both 10w-60 and fairly esoteric.
But if you feel like being the guinea pig, go ahead. PLEASE do UOAs before and after, and PLEASE post them here.