oil leak around spark plugs

Oil in the spark plug tubes is commonly caused by leaking O-ring seals. These seals are replaced as part of a valve cover reseal. Please use the following link to find the cost to reseal the valve cover(s) on your 2003 S-Type Jaguar - https://repairpal.com/estimator/jaguar/s-type

Be very delicate and properly torque the valve cover hold down bolts the plastic covers can warp. I use Permatex gasket glue to make sure the gasket stay in the valve cover.