oil on plugs

The plugs seals under the valve cover are bad and you need to replace them. Parts stores sells these seals in a kit, valve cover, plug seals and valve cover bushes. Som comes with an additional 4 O'rings, those are located under the cam carriers and I would not replace them unless necessary as it involves a lot of work, removal of the cam carrier and valve adjustment and even might require the timingbelt to be replaced if the cam seal is tampered with.