Oil on spark plug threads… what could it be?

[mkemp590]

Hi all, doing my first plug change on my 08 CS with 76k. I bought it with a new short block done by Porsche under warranty at 39k back in 2014. I’ve only had for about 1000 miles.
I already did the oil (0w40)and clutch/flywheel which was on its way out.
Had Blackstone analyze the oil that was in it ( not sure how many miles were on it but looked pretty normally worn) and all was good. The second time out since my clutch job, I got the p0421 warm up catalyst efficiency below threshold bank 1 CEL. After talking and a little research, I figured all the banging getting the exhaust off knocked the prone to fail honeycomb loose.
I have a Soul exhaust and the stock headers. I ordered some competition headers and figured I would call it a day.
In preparation for the new headers, I figured I would change the plugs while I’m there. Pulled bank 1 on the passenger side first. Plugs 3 and 1 have oil on the threads, while 2 doesn’t.
I haven’t made it to the other bank yet.
My question is, is there anything other than bore scoring that could cause this?! Oil level was good before I changed it. After the change, it’s right at the top line on level ground cold. Could it be aos related?
I’ll attach some pictures of the plugs and the analysis.
Thanks in advance for any help!

[Aaron]

There's only so many ways that oil can get onto the threads and they generally get worse and more intensive to repair the further down the list you go.

 

I would start with trying 5W/40, clean the plugs, do some driving and then check them again.  After that, you're looking at valve cover/plug chamber gaskets, then valve stem seals and eventually down to piston rings/bore scoring.  Have you had the cylinder walls inspected?  That could at least tell you it isn't the worst of the options available.