oil on upper end of spark plug threads near the ceramic part?

[Scott Douglas]

I know they say it's hard to read plugs now days with the unleaded gas and such, but I'd expect the tip of yours to be a tad browner than it is showing in your first picture.

I know when I had a problem with my Accord and pulled all the plugs out, they were uniformly tan except for the one with the problem. It was black and fouled shut ie no gap, with carbon.

[John Rogers]

My racing buddy Ted used to get that on his hot rodded 356 and it showed as a misfire and if he did not stop in the pits immediately very shortly there would be a "BANG" and the plug and threads in the head would just blow clean out! At Palm Springs races years ago it happened twice so he finally put in inserts for all 4 plugs.....no more issues.

I would suggest buying one of the small diameter bore scopes from either Amazon or Harbor Freight and your phone shows all so and issue in the cylinder(s) will show up very easily.
John Rogers the oldracer

[look 171]

Hey John, what should I be looking for?