Thank you for your post. Engine serial number is 104 992 12 034665--It does not have the coolant/oil heat exchanger installed. This does however make me curious. In my limited experience, coolant leaks around a head gasket usually cause a brown milky frothy buildup inside the valve cover indicating coolant is getting into the oil system. What causes oil to get into the coolant system? Does the fluid with the higher pressure get into the fluid with the lower pressure? Could some combustion air leaking through a faulty head gasket carry some oil into the cooling system?

Thanks again for your reply.