How long can oxycodone be detected in an oral swab drug test?

Permanently. Whatever you do, will show up in a hair test until the hair that was growing is gone. It will not, naturally, wash out of your hair as your hair is partially formed of the toxins in your blood. I refer you to this link, which is about marijuana, but the idea is the same: http://www.howtocleanyourbody.com/long-does-marijuana-stay-your-system-hair-testing-a-3.html