Q: I have a 2001 Lincoln LS and the spark plug on the number 8 cylinder is leaking getting oil on the spark plug what do you think th

Sometimes there can be oil on the spark plug threads but the plug itself is not fouled. If the firing end of the plug is OK (not fouled, and not covered with liquid oil and so forth), the cause of the misfiring is probably not the oil leakage but rather something else. If there is oil on the plug electrode and the plug is fouled, the oil gets in due to leaking piston rings or leaking valve guides and valve stem oil seals. You can try to gauge the condition of the rings, and cylinder No. 8 in particular, by testing cylinder compression in all cylinders. If compression in No. 8 is lower than the rest, there are tests that can help to gauge if the lower compression is due to ring wear. With regard to the valves, there’s a "possibility" that installing new valve stem oil seals could reduce oil leakage into the cylinder but, if the valve guide turns out to be really worn, putting a new seal on will be a very temporary measure. The bottom line is if the plug is oil fouled and a simple valve stem oil seal replacement is not likely to help, the engine will have to be rebuilt. If you want a definitive, on site diagnostic, please request a spark plug/oil leak diagnostic. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.