There are 2 options when it's all said and done:

1. Use the recommended BMW fluid: all the research has been done and the BMW engineers have concluded and guaranteed that this is the most suitable and best performing oil for your car. Takes away the guess work.

2. Do your own research: There are many BMW approved oils. I chose to use Total Quartz INEO MC3 5w-30. There are quite a few however.

Neither of these solutions absolves you from regularly checking your oil level and potentially changing your oil prior to the 15k interval. I change mine @ 7500. I feel 15k is just far too long for any oil, even the BMW one. It's just a personal preference and potential OCD complex of mine.

__________________
----------------------------------------------
2006 X5 3.0L - Schwarz Black/Truffle Brown
Stock
But I keep it clean