Spark Plug Insight: Clean Insulator in Bank 6 at 196k Miles - Normal or Alarm?

2014 V6. I usually change my spark plugs before or around 30k miles. Now my truck has 196k miles, and I've been the only owner. This last time I changed them, they had around 27k miles on the plugs. I noticed that the insulator from the spark plug in bank 6 is clean, unlike the others, which have burns at the base. I don't remember seeing this in previous changes. Has anyone else noticed this? Should I be worried? What are my plugs telling me?

In the picture, banks 2, 4, 6 are on the bottom side of the driver's side, and banks 1, 3, 5 are on the top side of the passenger's side, going from left to right.

Thanks you!

 

And now I can’t get that damn Sesame Street song out of my head…

 

The rest of them have blow-by and that one doesn't. I wouldn't worry about it. Probably just got a tighter fit during production.

 

Alright, knowing it's called "blow-by" makes it clearer for me. These spark plugs aren't from when the truck was made. I've been changing them every 30k miles, and now my truck's at 196k miles. So, if there was an issue last time, it was probably because I didn't tighten the plugs enough. I recently bought a few new torque wrenches because I ordered a Bilstein 6112/5160 Kit and an Icon RXT leaf pack to upgrade from my 5100's. I wanted to make sure everything was torqued to the correct specifications. This last time I changed the plugs and the PVC valve, I made sure to use the right specs.

 

Corona stain:

https://ngksparkplugs.com/en/resources/5-things-you-should-know-about-spark-plugs

Nothing to do with tight or looseness and it's normal