^^4oz is way too much unless you have a tolerance. Think more like 1-2oz. Drink it however, but it probably tastes nasty which is why mixing is so popular.
Hydrocodone syrup...had one of the most enjoyable opiate highs I've ever had on just a capful of that stuff (granted I had zero tolerance). Just off a capful, it's pretty nice stuff.
4 oz's is roughly 20mg's, sounds about right to me, but hey I shot heroin for years so I'd take Felonious Monk's advice and dose lower, for the respect of HR.