[jc_bmw]

Decided to finally change my Spark Plugs at 145K KM (~90K Miles) because my engine felt a little funny like a odd intermittent misfire. When I scan the car there were no error code.

After pulling the plugs, I have noticed cylinder 4 (count from the front) had some oil on the threads. No oil on the igniter or the coil pack. So I would assume this would cause my odd misfire (randomly in mid-throttle on the highway).

Now I am trying to figure out where is this oil coming from. Is it signs of a valve cover gasket going? Or a plug that is going and not burning everything off?

[zhp43867]

Start by changing the valve cover gasket, and inspect the pieces of the gasket between the spark plugs holes. My last 330 had a snapped stud there and would burn oil (smoke out of the tail pipe) under super heavy cornering. Also had oil on the spark plug. Replaced the gasket and stud- problem solved.

[greenberet123]

If there is oil in the spark plug hole, does it mean that the spark plug is destroyed and needs to be changed? Or can I just wipe out the oil and put the plug back in?

[bluewater328]

Originally Posted by greenberet123

If there is oil in the spark plug hole, does it mean that the spark plug is destroyed and needs to be changed? Or can I just wipe out the oil and put the plug back in?

If it's not fouled proceed on unless you have the originals in and you're anywhere after 80K miles. Quoted life cycle from BMW is 100k for a straight 6; but after 80k on the plugs and you got her open, just change. Here's a nice article that gives you an idea of what to look for:

http://www.underhoodservice.com/spar...g-diagnostics/

Not a do all end all, but helps. I was gonna post an NGK video but they go straight from perfect to utterly oil destroyed without any of the usual in between descriptions/visuals.

[arkie6]

Originally Posted by greenberet123

If there is oil in the spark plug hole, does it mean that the spark plug is destroyed and needs to be changed?

No. It just means, most likely, that your valve cover gasket is leaking oil, or possibly oil was spilled around the oil filler hole in the valve cover during a previous oil change or oil addition and it leaked over to #4 spark plug hole.

Or can I just wipe out the oil and put the plug back in?

Yes. You can clean the oil off the plug with a solvent or degreaser. The white porcelain insulator in particular needs to be clean to prevent electrical tracking and mis-fires to ground. If the oil comes back, you will eventually have to replace the valve cover gasket.