when day is hot or I have shaked the car a lot when driving I'm able to hear a WHISTLE comming out from gas cap ( Stant "vented" ) Whistle comes from rubber seal. I simply moves a little bit the cap and pressure is enough released to quit the whistle.

I have known the "vented" is mainly to allow the air get in as far fuel goes down BUT who cares about air coming in if anyway vapor gas presssure is getting inside ? it won't need get air in with all the vapors.

With a Charger born in Chrysler assembly plant in Valencia, Venezuela