Cylinder 8 on 1999 Ford expedition not working and oil on spark plug?

Cylinder 8 on 1999 Ford expedition not working and oil on spark plug?

Are you sure it's oil and not gas on the plug? Initially I'd say that cylinder isn't firing. Take the plug out be leave it connect to the plug wire. Lay it on the engine (ground it) then start the car and see if the plug is firing.