I bought a 2004 civic 1.7 with 174k. It had a obvious oil leak that the owner swore was from the valve cover gasket. Maybe it is. But can a head gasket leak oil and still have good power and smooth running? The oil trail was easy to see as it covered the front of the block on the left as your facing it. It was wet just below the head. If the valve cover leaked it would have to be on the left in the corners for the cam. There was grey RTV globbed in those corners. Head gasket or valve cover?

 

Clean all the oil off and watch for it to come back and trace it from there