This is quite normal and we see it often. You do have blow-by, but all of these do...I have gone as far as to seal the little can that is inside the aircleaner so the seams on the clamped top do not leak oil. Then the oil will just drain into the pan.
Caution!!! Do not block the blow-by hose!!! This will blow out seals.
1992 500E (very soon I hope
1981 280GE SWB
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM