daoh

I replaced my spark plugs today with the AutoliteHT0 plugs, and I was just curious if anyone knew what this brown dusty stuff could be on my factory spark plugs? It looks kind of like rust, but it is more of a brown powder than that orange-brown rusty color. The car is my daily driver and it really never sits for more than a couple of days without being run. I have just over 15,000 miles on it.

[IMG]local://upfiles/20225/D6D3924CAF8D4DBCBCA4DC3E2BFF9059.jpg[/IMG]

[IMG]local://upfiles/20225/919605E1BD5F43D2B20D9CF601D7E216.jpg[/IMG]

dmtGT05

carbon?
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daoh

That very well could be. After I rubbed the brown dust off, there looked to be some black carbon build up underneath it...hmmmm

Eleanor06

Yeah I had the same question awhile back.Turns out it's normal on our 3 valve engines.

moosestang

Techron.

8cd03gro

what kinda gas do you usually fill up with?

daoh

The best we can get here in Colorado, 91

281GT

Those are perfectly normal spark plugs. That color indicates your mixture is bang on and you're not using any oil. Nothing to worry about.

05gtdriver

Yes, yes, yes a light brown/tan color indicates proper and good combustion.....and that black underneath means you're not running lean.........

daoh

Thanks everyone. I knew that a light tan color was good, I just didn't expect the dust with it. Thanks again!