Cylinder misfire due to oil on spark plug


Dec 18, 2019
Chicago, IL
Hey all, I searched around but didn't see a thread dedicated to this specific topic; please link to one if I'm wrong!

I've had a #6 misfire on my '03 GT first about a year ago and thought I had fixed the problem by swapping the ignition coil. It's been fine since then until about a week ago. Same thing came up, #6 misfire. After popping the hood and removing the fuel rails, I found some oil sitting on top of the #6 spark plug.

I'm assuming and have read that a general culprit could be valve gaskets or piston rings, but anything I should look for specific to these Mustangs? My valve cover gaskets look fine too. I do pretty much all my own work and she's my DD so I try to avoid tearing her apart too much if it's not necessary. As I don't have gaskets to replace or a plan where I'm gonna start, I cleaned out the oil and buttoned her back up. She's been fine for the few days since, but I know it's a ticking time bomb.
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