Red spark plugs

[JPNinPA]

Changed out some spark-plugs on one of my jeep vehicles. I never saw red plugs like this before.
There was a jugger in the engine when keeping speed. I think one or two started arcing down the ceramic because of the deposits.

Never look down on anyone unless you are helping them up - Jesse Jackson

 

[TerryMason]

Is that from running lean?

 

[Jeepergeo]

I've see them like that before a long time ago and recall it happens with some fuel additives. See the link for plug photos.

Autolite Plug Diagnosis