BMW don't actually make oil do they, surely? Castrol are the masters of the art IMHO and I refuse thus far, to use anything else.
TB.
Firstly, refuse at your peril...but be stubborn if you wish.
BMW doesn't make much at all, certainly not oil. In this they are no different from most other 'makers'!
What they do do, is design, develop amd specify.
Their specification for the engine oil for the K12/3 was put out for tender, like most things; brakes, seals, bearings etc.
Whoever gets the contract to manufacture is bound by the T's&C's of the BMW contract which means that it can't be made, marketed or sold to or by anyone else.
BMW, like most makers, change suppliers from time to time. The old supplier knows everythimg about the product now being made by someone else but can't do anything about it.
So, Brembo discs and pads are made by Brembo (obviously
) but to BMW's specification. Buy the ordinary ones from Brembo and you might not notice the difference. Others in here most certainly can.
For the sake of the cost of a couple of tanks of fuel you can chance your clutch.
Me, I don't gamble.
PS I have no idea why you think Castrol are more the masters of the art of oil synthesis than any other major manufacturer. I understand your prejudice, the Duckhams oil mayonnaise in the '60's and '70's put me off their oils for life, but virtually all shelf oils are the same, spec for spec.
In respect of the oil for the K, it is the spec. that is different.