[mr0077]

David, I thought someone would have jumped in here by now, but here's my take...the plug looks, and from your color description, sounds somewhere between slightly lean to just about right, depending on the number of miles on it - if not very many, about right, if 500+ miles, a bit lean. But the base of the outer shell looks as normal as it can get...I think the shell runs a little cooler and gets some sooty deposits that are burned off of the insulator and the electrodes by their operating heat.
Any other thoughts, guys?