The diesel engine oil is about twice the price of the regular BMW oil. And there aren't a lot of diesels around. At that price, I would be a bit concerned that they might not use the expensive Diesel engine oil, since it is almost guaranteed to be a money losing proposition for them within a couple of years, e.g., based on what a parts guy told me about margins, the oil probably costs them $8 a quart, and the filter $14, for a total of $78 of parts at their cost. Figuring an oil change every 3 months, they will be "in the hole" in about 2 1/2 years on parts cost alone.

Maybe they haven't yet figured-out the higher cost of Diesel engine oil and filters, and have the same price as for the gasoline engines. Yours might be the vehicle that causes them to revise their pricing!