Found OIL in spark plugs AGAIN

[SuperAkumaGT]

I have a 2011 Subaru Legacy 2.5i 6MT with about 178k on it. I bought it brand new and the car is pretty much all stock.  About 100k I noticed oil in the spark plug only a little bit. I didn't do anything until around 150k when I changed the rocker cover gasket, spark plug gasket and new spark plugs  because the spark plug was soaked in oil. Car was fine, 10k later I checked the plugs again and it was still dry.  

Over the weekend I check it gain and because my car had really bad performance and gas mileage. I noticed that all 4 plugs plugs had oil in it and quite a bit.

Like almost all Subaru the car burns oil. Maybe 1qt per 5000 miles or so. There is NO oil leak ANYWHERE on the car. The last time worked on my car I checked the rocker cover and both side was dry on the bottom, this was a couple of months ago.

Is it usual that this would happen TWICE? I did the job myself using all OEM parts directly from Subaru. Maybe I didn't do a good enough job or is there something else bigger that is causing this to fail pre-maturely?

[DrD123]

Well, to be fair, you found 4 leaks if you have oil in all 4 plug tubes

I would check the pcv valve - make sure it's moving freely (or better, since it's cheap and takes some effort to get it out, just go ahead and replace it.  If the old one doesn't rattle back and forth when you shake it, it was stuck and that could be the issue.  If the pcv valve is original, at 178k miles, it's likely gummed up.

[SuperAkumaGT]

PCV valve was changed about 2 months after I did changed the rocker cover gasket. The PCV valve was all plugged up and cracking at one of hose. I replaced the whole assembly using OEM subaru parts. Would 2 month of driving cause the gasket to fail again?

Probably going to have to do it again, the parts are cheap enough just a PITA to do. Just want to see what else I should inspect and get this taken care of.