Alan - I agree and would not put it past BMW to put in what they had at the time and am sure more than the odd car has gone out with a dubious oil in it...
Jeff - Again I agree that any oil brand of the correct spec will do, however my thinking was more about the pedantic attitude of the service desk towards customer supplied oils.
All this said I have been surprised at times when oem supplied oil is cheaper than the general public can get it themsleves, especially when you add in the time and effort and petrol to go find it.
Frankly I do all mine myslef, my local indy stamps the book and I'm sure of quality and best price, but do know ther eare many reasons to keep the genuine BMW service.