I am no doctor but it is my opinion that you will go thru withdraw from the
methadone, which is much worse than hydro.
Methadone has a very long shelf life. Please be careful mixing the done with anything. A whole bunch of people that I know have died doing just what you are doing. Methadone stays in your system a long dang time. Be careful because when you play with fire you will get burned. If I were you, I would stay far away from the methadone. Just my opinion.