thanks to the help from this forum! I can now see oil pooling on the driver's side of the engine block, just below the starter and above the oil pan. I have new valve cover gasket installed. The oil filter cannister and related mounting is dry. Can't see the oil pressure switch, so I bought one and will replace it anyway. What else could it be. This is not a very slow leak, leaks probably 10 drops overnight on the floor. Thanks for any help you can think of. Keith