Lifetime Premium Member
Join Date: Nov 2018
Location: Southeast Michigan
Clean spark plug, oil on threads
I'm reaching out to the team to get some thoughts on my recent findings. I have about 550 miles on my newly rebuilt 396. I was doing some plug readings the other day, just to find that the #2 spark plug has oil on the threaded portion. The plug is burning clean and indicated it was slightly lean, so I corrected that by fattening up the jets by two sizes. Also, the ground strap indicated that the plug was too cold. What would cause the oil on the threads of the plug? I'm running 10w30 royal purple break in oil.