10:18 AM Today i replaced the spark plugs. I had NGK Iridium rated 75k that had been there for 100k or almost 5 years, mostly freeway. I initially ordered them on Amazon (i think it was the 100k type for 60 bucks) but the package was slightly damaged so i returned them and bought the 75 k type (not laser welded) from Autozone.

The gap was unchanged after 100k. There was some whitish deposit on one of them and a bit of carbon on the base metal on all. Those are mighty good spark plugs, i recommend to anybody.

When i got them all out i took advantage of the situation and stuck a borescope camera in there. Could not turn the camera towards cylinder walls to see if they still got those crosshatch patterns but i would not expect to have them after 180k miles.

I think i saw on one piston the same peeling white deposit i saw on that spark plug. Will come back with a picture.
 
I put back in Denso Iridium (50 bucks instead of 80 would have payed today for NGK on Amazon) and after a test drive i saw no difference in mileage but the engine does sound smoother. Got to do a longer drive to see.