Is oil on a spark plug really bad?

[064banger]

Misfire in cylinder 1. I pulled the plug and saw oil on the threads but not on the electrodes. Is this bad? I’m hoping it’s a spark plug cylinder gasket failure rather that something else. Any other ways to check?

It misfires most of the time at idle but occasionally it stops for a few seconds. Under any load it always misfires.

 

[CharlesHS]

Oil on the spark plug threads probably came from valve cover seepage.
You need to check the fuel injector ECU signal along with spark to that cylinder.
IF you have already checked these; then check cylinder pressure and perform a cylinder leak down comparing to the other cylinders.

 

[pagrey]

The first thing I'd do is swap two plugs. If it is a plug issue it'll swap cylinders. If it is a spark plug gasket issue re-installing the plug will fix the issue. It's an easy first step.