Mine had to soak one month and some change. See the yellow straw in the head bolt area ? Used 3/4 can of Kroil, and a third quart of 50/50 ATF/acetone .... over the five weeks. Sh#t, mine was a new motor supposedly. Popped the cover to adjust valves ... thought it was MISSING a head bolt .... NOPE .... broken during assembly. GRRRR .... I bought it from some rat bastard cheat .... obviously. So who knows ? In agreement on sh#t EZ outs. Yeah, don't use those on head bolts. Not designed for it. Buy great bits. Not cheap .... but you'll be driving. Is what it is.