Thanks. I wondered about this. It is a 420sel. I have been changing the Mobil 1 every 3,000 miles but have decided to up it to 4,500 - 5,000 because of the expense and lack of equipment I have on hand (I change oil and filter at a friend's that has a "working" garage - he goes to school in Illinois and is not home very often).
If this does not do the trick I will investigate and change out the "offending compensator".