Or even leaking valve cover seals.
Mine were getting bad on the 4.5 before the valve adjustment. At a stop light I could see tendrils of smoke coming from under the car. After doing the valve adjustment and replacing the seals there is no more smoke. Closer inspection of the pipes showed that oil seeping past the seals was slowly dripping onto the pipes from the rear of the head.
I think the oil dripping was the catalyst to get me to adjust the valves. Find the source, oil or transmission fluid dripping onto hot pipes could be a fire hazard.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.