Internal and External engine oil & coolant leaks can develop from the head gasket and/or timing cover gasket; these leaks should be repaired before the engine oil and coolant intermix which can result in severe engine damage.Google+
Car Problem Reports
Mercedes-Benz S600 Repair Leaks From Head Gasket/Timing Cover Gasket Before Oil and Coolant Intermix
Mercedes-Benz S600 Problem
Average Mileage: 109,000 mi (30,000 mi - 188,000 mi)
I have seapage at the timing cover but it has now been that way for 70000 miles and has not turned into a serious leak and doesn't drip or create much mess. My mechanic has cleaned it off several times while doing other work, like replacement of a water pump, but has advised against fixing it because the problem is so likely to recur and may actually be worse over time as it is hard to make the repair "hold" because this is a design flaw on the v12 engine in this s600.
Visitor, 1996 Mercedes-Benz S600, 188,000 mi