How a head gasket that is below the valve cover could pool oil in the bolt wells of a valve cover gasket doesn't make a lot of sense. The gasket inside the oil fill cap if more likely the cause and will set you back a whopping $5.

That motor is pretty notorious for leaking at the timing cover and that will generate a pretty fair amount of oil if left uncorrected. If it is leaking, there would be oil on the passenger side front of the motor down the front of the block and oil pan. It migrates back from there and can go back onto and past the transmission depending on it severity. It is certainly not unheard of for the head gasket to fail and especially if its getting some miles on it, however I would dig a little deeper on this one before you commit to the head gasket.

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1981 300TD
2005 C55
2004 E500
1999 ML430
1992 400E
1998 C43
2001 SL500
1988 300SEL
1986 190E 16V
1991 190E 2.6