I have been in search of a 530i sport for some time; i have noticed on 2 occasions that under the oil cap there is a layer of dark brown copper colour. Also when you look inside the engine once the cap is off, it looks the same. It looks like some kind of build up & can be scrapped of under the oil cap.
What is this?? the cars i have been looking are 2001\02 530i sports with 70.000 miles with full bmw serv history. I know they have had 1 or 2 bars on the service indicator, can it just be due a oil service?
Appreciate your responses: D