Oil fouled spark plug

We'll after 10 bottles of nitrous, my SOHC ZC has finally sprung a leak in the #3 piston. After inspecting the spark plug, it is showing wet oil residue around the plug. Besides the piston rings, could the leak be coming from headgasket failure, leaking valve seals or somewhere else. How can I determine the problem? I've done a compression test on all four cylinders and they are all within spec and the #3 cylinder does not show a significant difference in the test. I want to try to eliminate other possible causes before replacing the rings. Thanks

We'll after 10 bottles of nitrous, my SOHC ZC has finally sprung a leak in the #3 piston. After inspecting the spark plug, it is showing wet oil residue around the plug. Besides the piston rings, could the leak be coming from headgasket failure, leaking valve seals or somewhere else. How can I determine the problem? I've done a compression test on all four cylinders and they are all within spec and the #3 cylinder does not show a significant difference in the test. I want to try to eliminate other possible causes before replacing the rings. Thanks

You done a compression and leak down test? What are the readings? Could also be a valve, however you should see that on a compression/leakdown test too.

Does it run, smoke?

Could just be you foul'ed a plug? I went though quite a few sets of plugs when i was spraying.

Jay