#19 ARE the lower tube seals.

But did you have the properbolt tightening sequence & torque for those cam caps? How did the O-ring groove clean up? Any scratches or crud to prevent those from making a good seal?

 

Could a failure of the valve cover seals and the rocker arm seals both lead to oil in the tube. Or could one just result in oil on the electrode but not in the tube? Just trying to diagnose.

 

oil in the plug electrode is a different issue could be leaking valve seals and or worn piston rings

 

The question is how the oil got on the electrodes.

Leaking VC gasket or lower tube seals only gets oil on the outside of the plug. But sometimes there's enough oil that it gets onto the electrodes just as you're unscrewing the plug.

Oil that'sactually inside the combustion chamber can't come from those seals. Gotta be rings or valves...

 

So in other words its good that the oil is in the spark plug tube and not on the electrode- thus indicating bad seals and not bad rings or valves, right?

 

You got it! If it was on the electrod eventually you'd start seeing blue smoke blowing out the back and that's a bad thing...