My '12 X5D started dripping oil on both sides at around 40k miles. The driver side leak was chewed-up O-ring between the intercooler and th echarge pipe that goes to the throttle body. Completely my fault, because when i previously removed this pipe I didnt install the bolt that connects it to the fan shroud. It was moving and chewing the seal.
Passenger side was looking bad. All 3 oil supply lines for the turbos appeared to be leaking. To replace the long one that goes from the bottom of the engine block to the oil distributor block the low pressure turbo(the big one) has to be removed. I replaced only the top hose and the leak disappeared. It has been good for a few months. When it starts dripping again I will use the factory fittings and order a custom braided SS lines.