i have a 91 honda civic Lx with a d15b motor. the issue is about 6 months ago i was cleaning my plugs and noticed one and only one of the plugs had an excessive amount of oil around the threads, other than that the plug was fine. i decided to change the valve cover gasget and spark plug graumets. but this did not solve the problem as i discovered about 2 weeks ago. i was wondering if any of you have an idea of what can cause this, my engine has about 130000 miles.

 

On the threads or the electrode? Pics would be helpful.

 

threads

 

Is your car smoking?

 

seems like you are probably leaking oil through the valve guides in the head.