An engine Oil leak may develop from the PCV vent housing on the valve cover and/or the inspection plate on the front of the engine.Google+
Car Problem Reports
Mercedes-Benz GL450 Oil May Leak From PCV Vent Housings and Inspection Plates
Mercedes-Benz GL450 Problem
Average Mileage: 66,122 mi (12,500 mi - 150,000 mi)
Visitor, 2008 Mercedes-Benz GL450, 39,555 mi
oil leak from the top of the engine valve cover, dripping down to my garage ground.got fixed from the dealer
Visitor, 2008 Mercedes-Benz GL450, 107,000 mi
Was told of the oil leak behind the engine during a regular service repair/inspection.
Visitor, 2008 Mercedes-Benz GL450, 61,000 mi
leak from PCV causing smell of smoke
oil leak , wet hoses, going to bring back to dealer under warranty.