The spark plug in the #6 cyl of my 390 counties to get a light amount of what looks to be oil on it after the engine is run. there's a black mark on one side of the porcelain, oil around the the threads and even up to hex part on one side that you use a socket on to loosen or tighten.

Any ideas what could be causing this?

 

It could be the porcelain is loose in the metal part of the plug letting cyl compression work past, or do you have a valve cover leak over that cyl?

 

I'm pretty sure it's not loose, and there might be a leak. There's film around the spark plug between the to exhaust runners.

 

i've got a tractor that does this, but the problem there is a scored piston wall which causes oil to get past the rings.

'course, it smokes pretty bad too. unless it is under load, in which case you would never know.

not tryin' to pee in your cheerio's, just wondering if it is possible that you have an internal problem. you would notice the smoke at idle if it is anything like what i got going on.

just throwin' out ideas.