Once upon a time it was the color of your plug that proved your mix was on the money. The smoged engines had white plugs and never got any color till the day they died. My mix back then was richened till it gave me a nice light tan in only a hundred miles or so.

My 93 SC400 has had the plugs replaced after only a couple of thousand miles because I upgraded the plugs. In 2 thousand miles the NGK plugs were solid "brown". Is that normal? I pulled the #1 plug after I installed the Platinum replacements and it was brown in only a thousand miles. I can't see these plugs or any other going a hundred K like most books say they will.

Opinions? Facts? Hunches? Rumors?

Thanks for your help

John