I had a 1991 mercury topaz from new and at 110 thousand km.66 thousand miles my valve cover started to leak.the cover had a gasket built into it and was 200 plus to replace .I went to the junk yard and got a older cover for 5 bucks and a new gasket as the old cover required a gasket.I cleaned the cover strenuously.changed the aluminum cover and the origional cover inside was shinny like new aluminum .The car from new had synthetic oil and once seeing that synthetic keeps the innards very clean .sorry for the long story .
