Oil on lower spark plug only, not valve cover

[2011reptar]

2011, 115k. Have had a slightly rough idle issue for a while. Changed all 16 plugs and 2000 miles later decided to pull them again to check gapping. All gaps were correct but I noticed two of my lower plugs have oil on the tip that’s in the combustion chamber. I confirmed this is NOT a valve cover leak. Any ideas on what may be causing this and if it effects much? I understand the top plugs do most of the work and the bottoms basically just help with emissions? Anyway, not sure how to resolve this issue if someone knows what can be done, I hope it doesn’t require pulling heads.

 

[pcs]

any pics of the plugs? what other maintenance items have you performed? if you have no engine lights to point you in a direction, you can address the idle issue with easy maintenance items. clean the throttle body, MAF, and possibly use a top end cleaner. when you changed the plugs did you inspect the coil boots? 2 decade old truck going to need some tlc. all engines will burn some amount of oil. it can come from blow by past the rings, pcv stuck open, worn valve guides or valve seals, etc.

 

[Mad Zeus]

I didn’t have the rough idle . About half my lowers had a little build up the rest looked new . If your loosing oil I’d be concerned if not drive faster it’ll burn it off . Did you replace the coils & wires ?