Getting my car dialed in to perfection. All my plugs are tanish except no 6 it looks new. It is firing verified spark. I dont get why it would look new. Compression is fine. 4, 5 tanish 6 white electorde looks new with a slight discoloration. When i pulled the old plug out it was dark. Sooty. 4 5 where as well. I am wondering if i need to just up the mixture a tad. Does #6 run lean normally?