oily plug mystery
 

I was in the process of a spark plug swap out on my '05 C230 K 4 dr. sport sedan when # 2 plug came out drenched in oil. Oil was present in the bottom of the threaded plug hole. Oil level feedback showed normal. Buttoned everything up, using orig. plugs and started the engine. No problem at startup with smooth performance during warmup. Recent oil change, but I can't account for any problem that would effect # 2 cyl. :confused:

Oily PLug
 

Is your car still under warranty? If so I would have the dealer check this out. Shouldn't be any oil on a plug on a car so new, unless your a hard driver? :)

Hard driving didn't cause it
 

You must be loosing oil some time. You can't have an oil soaked plug and not be burning oil in that cylinder. The engine has a problem. Might well be a valve seal, it could also be a valve guide. It has to be some where. I would say valve seal. Engine speed, or hard driving has little to do with it. I would think the quickest build up of oil on a plug will appear with slow easy driving. Hard driving will leave a charred residue.

Is the electrode part of the plug covered in oil or the outside? From your original post it would seem that the oil is on the outside. If that is the case then the o-ring that seals the plug well off from the head probably went bad. It s a cheap part to replace but you will have to pull the valve covers to do ti.