strange one this…(at least with my limited knowledge of engines)

Changed the spark plugs on the car today (MK1 Focus, 1.6)

The threads were coated in engine oil, a little alarming. But the actual electrodes, while not the browny/grey they should be, werent coated in shiny oil.

Put the new plugs in, fire it up. Sure enough the exaust is a little smokey, but this soon subsides.

MPG is normal and its not burning excessive oil (for an 117k motor…)

Any ideas? I dont think oil is leaking into the cylinder during operation, as the exhaust would be smokey and I’d be regularly topping up, neither of which is true.

No help but I saw the title and thought of this.

tbh not all in fact few plugs would be the light dusty ochre espeically if the car had been driven through traffic and stopped normally outside your garage/ on the drive.. the only way to get a good plug reading is to drive up a nice long hill flat out and cut the engine that should give a real indicative visual.

Does it smoke a lttle when it has been stood for a long time i:e overnight and then clear after a short while.
If so could be valve stem oil seals

not sure, I will check when I next fire her up

Maybe the cam cover gasket has a slight leak where it seals round the plugs, and in withdrawing your plugs you’ve exposed the threads to the wee puddle of oil sitting in your plug recess, therefore coating the threads in oil. A small amount of oil then drips into the combustion chamber because theres no plug to stop it, and it burns off upon start up.
Nowt to worry about. 😀

^^^^

As he said.

Sure it was engine oil?

The diligent mechanic who installed those plugs will have coated the threads with coppaslip or similar anti-seize compound, especially if it is an aluminium alloy head.

Neil F is on the money.

on an overhead camshaft setup, oil around the camshaft area commonly weeps into the open space around the spark plugs and runs down to the area around the plugs themselves. unless there is a massive puddle of oil around the plug, then a wee dribble isn’t too much to worry about.

Is it oil on the threads or just carbon deposits?

If the plugs aren’t a tight fit in the heads (washer missing) then the gas in the cylinder can escape and leave a mess on the threads as it leaves while the rest of the plug looks fine, solution is new plugs and washers.

Its definitely oil on the threads, and not just a small amount (in some cylinders).

THanks for the replies so far