I am doing the first plug change on my 2012 with 31K and P30 package. All the plugs including the electrodes look good but the #6 plug has corroded and has white powder on it almost like the powder on a corroding battery terminal! However the electrode looks normal. The corrosion includes the gasket and there is some residue at the bottom of the valve cover insert next to the cylinder head threads but no damage. The plug was not hard to remove. There was no sign of any moisture or leaking anywhere on the engine and the engine has never been power washed. I have had an occasional misfire from the engine over the past few months but the engine always has thrown a code for the #7 cylinder, never #6. I carefully inspected the coil pack and could find no signs of damage or spark tracking on the boot. I have enclosed a few pictures. Any help will be greatly appreciated! Thanks!

 

Coolant?

 

dielectric grease of some sort inside the plug boot to prevent water/oil to creep up is my best guess.

 

Looks to me like a little moisture has seeped past the seal to the valve cover on the bottom of the coil pack. I noticed a few spots like that on my plugs when I changed them.

 

That makes sense. About 3 years ago the car sat for about 9 months without being driven. I bet some moisture got in there. Thanks.

 

I thought the same thing. He said this is the first change so a lot of years to get to this state.