I got a CEL P0304: Cylinder 4 misfire detected. I went and got some new spark plugs to put on. Upon pulling out #2, there was a small amount of oil that had build up/dripped out off of the end of the spark plug wire. I wiped it off and pulled out the spark plug. There was no oil visible or within the spark plug (where it ignites) and it looked okay (normal). Do you guys know why there was oil there? There were no oil in any other ones. Thanks in advance.