I replaced the OEM plugs as preventative maintenance as my driving falls under severe service. They were a bit difficult to remove from the aluminum head but I gingerly loosened then tightened then loosened until it smoothly loosened out. OEM gap is .039-.044; all the old plugs were at .043-.044.
These plugs were replaced with NGK Iridium IX (on the right) plugs pre-gapped @ .040.
Why are the threads damp with oil? I can say I looked into the spark plug wells before removing the plugs & they were clean & dry. Car runs just as good as before; maybe slightly smoother & 1-2 MPG increase.
How do they look? Thank you all in advance.