When the motor is warm but not hot, put a disposable glove on and run your fingers around the bottom of the valve cover where it meets the block, especially back behind there by the firewall. If oil is on your fingers when you pull your hand back out, it is probably leaking. You should be able to see a leak over the exhaust manifolds, as there is a little heat shield over them that oil collects on if your gasket is leaking to that side.

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2001 E53 3.0 5pd