So i checked into my local BMW service station in Port Chester NY just to get an idea of what it might be. The person behind the service counter stated the VTG oil needs to be replaced in the transfer case.

Not quite sure what that is. Ive never had that done before. He quoted me about $150 labor plus the oil. Parts had the oil for $25 a quart.

He mentioned the service notification can go on at 60k, 100k or when needed.