Air coming from oil fill hole - PCV?
 

2007 with 139k miles
Just noticed when the car is running and you take the oil fill cap off, there is lots or air coming out. More than normal.
If you put a piece of paper to it it will flap around like crazy.

Does this mean bad PCV valve or perhaps its clogged up?
Will SeaFoam help unclog it? I know its burried down there so not easy to replace.

What do you mean more air than normal?

I'm pretty sure that's normal. Engines work in the suck/squish/bang/blow. You're probably getting the typical blowback out of your oil cap.

I mean i owned many civics and such and never had this much pressure come out when taking the oil cap out.
Maybe its normal for the fit?

At idle there should be a suction under oil filler cap. Suction should hold unscrewed cap to the top of filler neck at idle. Pressure under it at idle means stuck closed PCV , clogged hose between pcv and intake manifold or clogged intake manifold pcv holes
https://cimg7.ibsrv.net/gimg/www.fit...aee831c3fb.jpg
PCV passages
If all clear and working, the piston rings are shot
There also could be be some oil around dipstick tube and inside of the air intake

Ok thanks, i will take the air intake off and check the PCV tubes first.

Take pcv hose from the intake when engine is idling (hot) if rpm goes up and the suction is felt at the intake fitting , the holes are open (but can be partially blocked as well) In cold climate too much moisture from combustion (ethanol fuels( can freeze at the valve until engine fully warms up

I’m having the same problem and I took off the intake manifold and there was a ton of carbon in it. I was able to get the intake nozzle to suck Sea Foam but found oil in the PCV valve. After testing the PCV valve it never clicked. If there’s anything else it could be before it’s the piston rings?