Finally got my new Splitfire coilpacks from Slide tonight. While I was fitting them up, I thought I would check the spark plugs. The car has been running on "not all 6", so I thought it might have been a coil. Last time the engine ran like this, a piece of piston was playing pinball inside #2 chamber, and had punched the gap on the plug to nothing.
Anyway, found all plugs were generally nice and clean, 1 or 2 were a little black, but not bad. But #4 had a oil obviously coating the electrodes (these are Iridium plugs). Gave it a bit of a wipe down before re-installing it, because I don't have spares.
After all back together, fire the engine and engine runs smoothly.
But I'm concerned about the oil. What's your diagnosis?