i always clean the valve cover flange with rubbing alcohol then i like to use a CORK gasket. i run a bead of rvt. on the valve cover side of the gasket and place it on the cover. i then smear a thin layer of vasoline on the head side of the gasket. that way later on if you have to take it off it doesnt tear the gasket and its attached to the valve cover so it stays in place during install.