WARNING: This page is about a different car, the 2005 BMW 645Ci and 2004 BMW 645Ci. However, it is still accessible from the selected car via links, so may be relevant.
Install special tool 13 3 063 and special tool 13 3 061 (pressure gauge).
Start engine and check engine oil pressure.
Specified value.
Fig 1: Checking Engine Oil Pressure With DIS Tester