2011 F150 FX4 5.0, 102K miles-I changed the spark plugs today and 1 plug had oil on the threads but none on the end. Otherwise it looked good, like all the other plugs. Gas mileage has not changed, no lack of power. Any idea why this would happen?

 

Valve cover gasket may be allowing oil past

 

Its just leftover residue from the anti-seize applied on the threads from the factory. Nothing to worry about.

 

Oil on threads, anti seize, never heard it as that but I am no mechanic, thanks for chiming it.

 

I don't think it is anti seize, it was actual oil on the threads that I wiped off. Also, small amount of oil in the tube. I'll report back after I talk to my mechanic. Someone mentioned spark plug gasket?

 

Ah, sorry about that Jax. I assumed your description meant there was no oil in the tubes / on the top of the plugs. I think like caperj pegged it - valve cover gasket.