Tap, Tap, Tap...
bg moa is a really good addiive. if it is a lifter sticking put it in with the engine ideling and you can hear it go away lol its kinda cool. but any additive would just be a bandaid. maby a bandaid that as long as u keep it in its fine but i would try to track it down more. maby get a stethscope and pinpoint the area then dig in lol