So recently I had my cylinder 4 spark plug back out and strip the threading on the head on its way out. A shop tapped it out larger and added a spacer, and all seemed well. They said they checked compression and it was great. One of my coils was a little damaged when the plug came out so I got a Sparktech non-CDI unit and put it in. I checked the gap on the plugs when I did so, and I noticed some oil on the flat part of the #4 plug above the threaded section. I checked my oil and it's still fine, and I don't have visible oil smoke coming out of the exhaust so I know it isn't a huge leak, but is it my head gasket? Can I expect it to get worse quickly or do I have some time? Any other theories?

 

Valve cover gasket ...

 

sounds kinda like u cracked a piston. the car will run normal and still have good compression as 90%of the piston is in tact but 10 percent of the ring landing may be missing.

Or
valve stem seal.usually will notice smoke from this though.

headgaskets rarely leak oil into cylinder's

I would say get a leak down test done and that should tell you all you need to know about the issue. if you cant find some one to do it email me and i may be able to help

 

Would I hear anything from a cracked piston? Stuff rattling around in there or anything? I shined a light in and couldn't see anything obvious, but without a scope you obviously can't see everything. And the reiterate, the oil isn't on the threaded part of the plug that is down in the cylinder, it's the smooth cylindrical part "above" that.

I'll check the valve cover gasket. Doesn't that usually leak to the outside though?

 

pistons that are cracked dont always make noise and usually wont see it. however if you are seeing oil on top of the spark plug as in CERAMIC white part above you may be missing the spark plug grommet/seal it uses 4 of them for each cylinder and can be seen just by looking down the whole you will see a black rubber seal towardes the top of it. if not then its gone

 

So the oil is where on the plug? A part that is inside the cylinder or a part that is not in the cylinder and only inside the spark plug tube?

Is it wet inside the spark plug tube? Is it wet on top of the piston?

It sounds like its just the valve cover gasket ring but if it is inside the cylinder part then its from the intake sucking in oil from the valve cover via pcv valve and the first port it runs to is #4....Look at my pic and you'll see what I mean since it is what I found in my case. Although it's not number #4 its #3. At least I'm pretty sure it's the reasoning for mine, I just dont know why it wouldnt be in my #4 also but you get my point. Prob just the valve cover tube gasket though, you can see it when you look down the tube it looks like black rubber oozing out, depending how tight the VC bolts are anyway.

 

This isn't the actual spark plug, or even an Evo plug. I just googled a picture to show where the oil is. Shining a light down into the cylinder, the piston doesn't look shiny/wet.

 

Like i said valve cover gasket....

 

Have you looked to see how well the insert the shop installed provides a a nice smooth lip for the plug gasket to seal to?