Why is there oil in the spark plug well?

"In my case it was a bad spark plug well gasket. Oil gets inside the tube and causes cylinder misfire. You always need to replace the valve cover gasket as well. On 2002-2006 model spark plug seals are embedded into the valve cover and it’s impossible to replace just the seals. You’ll have to buy valve cover.

You can find step by step instructions and more details such as torque specs and sequence, silicone gasket maker application, tools and parts needed, etc. in the following video:

http://www.youtube.com/watch?v=JQmMdfEGw..."

I'm and owner and a licensed mechanic, problem sounds like you need to replace valve cover and gasket to fix the leak around the spark plugs, then check your ignition coils and plugs may need to be replaced from the leaking oil , white smoke comes from the engine burning oil that leaks inside the valve replace them and problem solved reset codes and be on your way

I have a 2003 nissan altima and recently had the valve cover gasket changed and was told that I had to change the valve cover as well because the the seals in the valve cover where the spark plugs go are not replaceable so even if you change the valve cover gasket oil still gets thru the seals up top and on your plugs resulting in your car misfiring and smoking ...you can get the valve covers on ebay fairly cheap or there about $150-200 @ the dealership hope I helped you out some..

For a temp fix you can go to your local parts store and get high temp sylicone gasket maker. I had the same problem on my 03 Nissan altima. Just fill the gap between the valve cover an the spark plug well and let it cure for about 12 hours this will not perminately fix the problem but should get you by until you can get a new valve cover.

"Oil in spark plug wells is almost always caused by an old perished gasket. After a number of years the gasket shrinks due to constant heating and coiling cycles and from the contaminants in the oil. Oil like water and electricity always finds the path of least resistance and after some time, creates a big enough gap to allow more oil to flow in to the well.

Once your plugs have bathed in oil for awhile, they are pretty much done. And even if cleaned up should really be replaced. As the ceramic can no longer efficiently dissipate heat. As the oil level rises in the well it moves it way up to the cap of the plug. Oil however won't really affect your car by causing misfires, as all it might do is create a bit of resistance and oil doesn't tend to conduct electricity.

The main causes of misfires are electrical faults within the ignition leads or faulty plug. Again heat and cold cycles tend to cause the leads to break down over time, usually on the inside where you can't see it.

If the engine starts OK and runs when cold then starts missing and jerking. The ignition leads are most likely at fault. As they tend to be 'tighter' when cold but as the leads heat up, everything expands and that close gap widens, and the electricity needs to jump a wider gap, this can happen numerous times in a damaged lead. So in the end the spark at the plug is both weak and erratic."