GT3 Misfire and badly glazed spark plug insulators

[meats]

I returned yesterday from a weekend of driving at Infineon and noticed that instead of the usual black exhaust tips, I had rust colored tips. My concern is that the the last time this happened my car started to misfire and I had to replace the spark plugs, as they were incredibly glazed over. My mechanic said it was likely due to the previous owner running leaded fuel. At the time I replaced the plugs, and until this weekend noticed nothing strange. I have not noticed any misfires yet.

One other detail is that most of the time I fill up with Chevron 91, but for both the autocross and this weekend I had been using VP Racing 93 unleaded. Anyway, is the rust exhaust normal after a weekend of track driving? If not, any idea of what is going on? cheers, Paul

[DavidNR]

No worries, most GT3's I've seen look that way after a DE. 3 years on the same plugs. My shiny polished tips turn bronze too.

[meats]

Good news. Thanks

[clord]

Did you happen to add any "octane booster/improver" product to your gas tank for the weekend?

[meats]

I did not use any kind of additives. Just pump gas from my local station. (Yup, there's a VP Racing station near my house, not at the track). cheers, Paul