[thumbdoctor]

The silver ring on the ground electrode method of reading spark plugs seems to be more effective at reading carburetor jetting on small engines and two stroke cycle engines. I have written many blogs on this subject for snowmobile/motorcycle sites. In all honesty, I don't think you have a big concern with this cylinder. As stated, there are many different kinds of carbon deposits that present themselves on today's spark plugs. I've had orange coloured deposits show on race car plugs (using race gas). After speaking with with the nice folks at VP fuels, it was discovered that one of they're blend additives contained red dye.