Not better, but safer because there is no debate whether or not you used the correct oil, if you get into a warranty coverage dispute at some point. Not something I would lose sleep over.

Any API-SM oil of the correct viscosity is fine IMO. The BMW oil sometimes has the BMW LL (long life) certification, but not always, it depends where BMW bought that batch of oil from. The BMW bottle isn't more expensive where I live, so I just buy it at the dealer (in my case it is Castrol 5w-30)

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue