Iridium:
http://www.pacific-audio.com/perform...es/267866.html
A new spark plug has been released for use in the above vehicles. The new spark plug has an Iridium tip instead of the current Platinum tip. Due to the different tip design, the gap of the spark plug has also changed. The new spark plug, P/N 12571164 with AC Delco P/N 41-985, is gapped to 1.01mm (0.040 inches) when the spark plug is made. The spark plug gap is set during manufacturing and should not be changed or damage to the spark plug may result. Any new spark plug found to not be properly gapped should not be used.
Damn, I thought I could find it with a simple search on the web. I guess "gap" means different things...
I can't believe it is not in the owner's manual. Or is it? I cannot check right now.