Plug Readers Chime In

nm9stheham said

I've seen blue, green, and rose colors on plugs in the past..... always figured it was from additives.

IMHO, the above 'lean and hot' reads are getting fooled by the modern fuels. Put an AFR gauge on it, and it will be in the 14-15 range cruising (maybe a tad higher even), which is fine, and really where it is supposed to be for regular driving.

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Thanks, that's good to know.

The top plug was a tank of pure 91 octane, non ethanol running 65mph for about 140 miles.

The same plug posted just above is a mix of 91 octane, non methanol and 93 octane Shell with a combo of 45 miles, mostly highway at 60mph and 35mph in-town.

Can an AFR gauge be hooked up temporarily without having to tap into the exhaust system?