http://dragstuff.com/techarticles/how-to-read-plugs.html
50 cents worth of free advice... You can't tell an awfull lot about mixture
from plugs that have been in that long. Put some new ones in and do a series of
"throttle chops" some calls it "plug chops". I will do one at cruise throttle,
and one at WOT for about 5 seconds. I'll read the idle mix from rolling through
the neighborhood and into my garage.
FRED hit it right on the head, saying your plugs show a bit rich. That's prolly
because you idled it up into your garage just before pulling the plugs.
Most engines idle a little smoother on the rich side so, you have the ECU just right.
One more thing I see with the second set (CO +3). Some time recently, you let her idle
(rich) long enough to load the plugs a little, then put some heat in the engine and
baked or fused some of the carbon. (The shiny blistered appearance of the deposits)
Not unusual, but you should remember not to let her idle for long periods.
What you CAN tell from the plugs in the photos is a generally healthy engine.
And that yer mechanic failed to use Anti-seize when installing the plugs.
