Mine has had a weeping headgasket leak for 130,000 miles. No symptons other than loss of coolant. No cross contamination of oil and water. Plugs look fine. Runs fine.

Headgasket is not a big deal. Under $1,000 dollars at an indy. Do the seals. Valves won't need it yet.

Steve
'92 300E 245,000 miles