Rep Power: 0

What is causing my spark plugs to have oil? I was changing my spark plugs and I noticed that the spark plug has oil on 2/4 of them. I changed my spark plug tube seals last year as preventive maintenance So I don't understand how it happened. Only the 2nd spark plug to the left is leaking oil.

 
Rep Power: 517

Plugs cannot leak oil. They don't have oil inside them, and there isn't supposed to be oil on either side of them.

Did you find the plugs swimming in oil from a valve cover gasket (tube seals) leak this time?
Were the plugs cleaned spotless from the leak the previous time, or replaced?
Were the coil boots cleaned or replaced?


I have found plugs with residue after running the engine for a long time with the plugs loose, some installer didn't get them tight enough to squash the gasket and then combustion gases seep past the threads....and usually when this is the case, the plug has a lot of resistance as you unscrew it because carbon builds up in the threads.....and the boot is also covered in soot or brown residue when there's been a lot of leakage, sometimes the plug is discolored from getting very hot as well


Really, if it's not the above situations, it's nothing to worry about.
A darkened ring found around the porcelain in the (exposed) space between the plug wire boot (or coil boot) and the steel is very common. It's caused by high voltage corona discharge, called a 'Corona stain'. It's very prevalent in engines with plugs deep in a semi-sealed tube

LINKY CLICK:
http://pmmonline.co.uk/technical/spa...-corona-stain/