Hello Chaps. I have a w220 - 2000 model s320 petrol. The car has currently done 93400 miles and was last serviced at 88000 miles with a complete oil change, spark plugs, files, etc etc etc. It was service A. this is back in 2009 and now my service reminder for service b is up and I just thought to check the oil level and rest of the stuff. As I opened the oil filler cap and I saw something of a different sort, black oil color and a bit goldenish stuff. I dont know what it is or how it occured. This was after the car was stood for 6 days of non driving and after I did a 100 mile return trip, the oil filler cap was perfectly black. So i dont know wht is it. Is the engine going... Also just to mention, at the last service the oil put was Mobil 1 - 0w-40. Is it because the oil is too thin.. Your comments are always appreciated.