2012 4runner...oil on threads of a single spark plug.

[N Heat]

I just changed my plugs at 192k and noted motor oil residue on the threads of the rear plug on drivers side. The engine runs perfectly and it doesnt look like Im using much, if any oil according to the dipstick. It has had an OCI of approx 8k on a variety of 0w20 oils over its life, the last 2 being Idemitsu. What, if anything, would you do at this point?

 

[Stonemason Jason]

I had a similar problem on my HHR a while back, I changed my valve cover gasket & spark plug tube seals.

 

[spasm3]

Not much, I would suspect a valve cover leak.

 

[N Heat]

I was thinking valve cover too, but the engine has long tubes that connect to the coil packs and I didnt note any residue on the tube or the deep cavity that the plug sets down into.

 

[ZeeOSix]

What do the ends of all the plugs look like? Does the plug with oil in the threads look different (darker end color) than the plugs that have dry threads? Could be using a little oil on that cylinder. If oil consumption isn't noticable or bad, I wouldn't worry about it. Do the plugs actually have 192K miles on them, or was that just the miles on the vehicle and it's had plug changes before?