Oil on spark plugs?

I have a 98 nissan 200sx 2.0 L engine with 185000 mi on it, A few weeks ago I started having issues with the motor sputtering and took it to autozone where they told me that my # 2 cylinder was miss firing and something about a knock sensor.

I went and bought new spark plugs and that is where I found oil in my # 1 and 2 cylinders. How bad is this and how much and I looking at for repairs

It could be as simple as replacing the valve cover gasket. There should be o-rings to seal around the spark plug wells to prevent oil getting down there. On some cars, there is another o-ring at the bottom of the well that can leak. These are harder to get to.

If the oil is on the outside of the spark plugs (the ceramic part) you need a valve cover gasket set, which has new spark plug tube seals. That’s what’s leaking.

If the oil is on the tip of the plugs, coming from inside the cylinders you have a much larger and more expensive problem.

I’m guessing it’s the tube seals. This is a few dollars at the parts store if you’re willing to replace the gaskets yourself.

There was oil on the inside of the plug where the spark is made and on the ceramic part as well. How much could I be looking at?

I would start by replacing your valve cover gasket and tube seals (tube seals are included with the valve cover gasket), spark plugs, and spark plug wires or boots, whichever the case may be on this car. The oil may have gotten on the electrodes during removal of the spark plug. If not, the oil indicates a major engine repair, but I doubt that is the case unless the car has been flogged and neglected.

The plugs are out. Run a compression test. If oil is coking on the tips of the spark plugs then you likely have an engine problem; probably piston rings.

The knock sensor may not be bad. If oil is being forced into the combustion chamber on those cylinders due to bad rings this will dilute the air/fuel mix and lower the octane a bunch. This can cause knocking which the knock sensor and ECM can’t control.

If the oil is on the tip of the plug, compare the residue with these photos.

Different types of residue present different possible problems. And accurate assessment of the type of oil resiude can help diagnose the cause.

If it’s raw oil on the topp portion of the plug, go with the tube seals suggestions.

Oh no thats not the case. Ok I will do all the above. One last thing, can a parts replacer like me take on changing out the valve gasket myself or should I have someone do it. I’ve been around cars most of my life but can’t say I’ve ever done this. By the way I’m a school teacher so money is an issue, but if I’d be better off paying someone than I will.

The oil was puddled around the base of the hex and when removed the oil ran down on the electrodes. Get NGK or Denso plugs that are recommended by Nissan and install them using anti seize after replacing the valve cover gasket.

I highly recommend that no plug other than the brand and part numbers specified by Nissan be used.