Ok, this is experience with the 4.0 again, but the breather on the throttle body is probably nothing more than to burn off excess gasoline vapors from your canister. If its a little 3/16" or smaller line, thats what it is. If oil is leaking from that, it is coming from inside the intake manifold. The PCV line goes from the valve cover to the intake manifold. It is about a 3/8" hose. The PCV valve can go bad and cause some oil to be sucked into the intake. Once you find it, they are super easy to replace. DO NOT put anything in your engine oil. It will do nothing, and can cause all kinds of problems.