FWIW, I got 150K miles out of my factory plugs, which, IIRC, were Iridium plugs. The boxes for the Motorcraft (often OEM'd by NGK) iridium plugs I just put in my truck specifically said not to regap them due to concerns about damaging the electrode; I believe it was because iridium electrodes are more brittle than traditional or platinum electrodes, but I don't recall where I read that.Also these are iridium plugs and they are supposed to wear much more slowly.