Oil on my plugs

I pulled my plugs out today to check the gap and found there was oil on the threads. What will cause this and is it expansive to fix?

Having the year, make, and model of vehicle always helps us help you.

My guess is that you have an engine with high mileage and spark plug tubes. The seals on these tubes can develop leaks that allow oil to get onto the plugs from the outside of the threads. In short, it’s probably not coming from inside the cylinders, but rather leaking past those tube seals.

How much it’ll cost to repair depends on the vehicle.

So probably oil from the valve cover area that is also supposed to shield the spark plug tubes. What car, make model would be helpful.

We saw this a lot on BMW V-8’s it never led to a more serious concern, but I guess it is possible.

Sorry…it is a 1999 Saturn, has 126,000 miles on it.

1999, Saturn SL 2

Yeah, you have spark plug tubes and the seals are leaking. It’s harmless.

However, I just notice dthat you said you pulled the plugs to “check the gap”. While I commend your prudence and integrity, if plugs have flat seats with metal compression washers, those washers are only designed to be used once. Once they’re compressed to a specific surface their ability to seal when reinstalled becomes compromised. The torque spec is also based on compression of these washers.

I honestly do not know if Saturn uses these or conical seats but it’s just intended as a tip.

Thank you

I am not sure if it is harmless. As far as I know when this gets worse it would cause misfire. Fixing it is not difficult in most engines. Needs a new valve cover gasket set and a torque wrench and 30-60 min of work.

sometimes when starting it,it stalls and I have to press on the gas to keep it running for about 6 to 8 secs and some smoke comes out the exhaust. Then it runs fine.

Aha! The plot thickens!

If the smoke is grey/blue, my guess is that you have oil leaking past your valve guide seals. There are seals around the valve stems that prevent the oil that lubricates the valvetrain parts from dripping down into the cylinders. When they leak, oil can run down past them as the engine sits idle and drip and collect in the cylinders (if the valve is open) and onto th eback of the valves (for those that are closed). This oil gets burned when you start the engine.

NOTE: that does not mean that the spark plug tube seals are not leaking. It just means that all your seals are growing old together.

However, if the smoke is black that’ll mean that you probably have leaky injectors and the gas is leaking when you shut the car off (the fuel system is still pressurized at that point) and sitting in a cylinder or two waiting to get burned.

should I have this looked into…will it get worse?
The smoke is not black.

On a 10 year old Saturn with that kind of mileage? Naw, I’d just be sure to keep routinely monitoring the oil. And perhaps throw some new plug sin now and then.

It’ll probably get worse over time. But it isn’t the kind of thing that will suddenly cause catastrophic failure of the engine.

Others may feel differently. Many like to fix whatever can be fixed without excessive teardown. Persoanlly, I’d consider the valves stem seals excessive teardown on this vehicle. You’ll need to remove the head, the valves, redo the valves and valveseats…naw, I wouldn’t bother.