Lately I thought I felt a slight skip in my car at idle. I decided to check a few plugs just to see how they looked. I checked 1, 3, 5 and 4 because they're the "easy" ones to get to. This is number 5:
Any thoughts on what might be causing that? I suspect my car has bad valve seals due to the oil consumption, and I've seen pictures of plugs that had deposits like that and it was caused by oil. Number 1 looked like that but not as bad, number 3 looked fine, as did number 4:
I've got some brand new NGKs ready to go in but I would love to resolve this issue before I install them.