The best way to know if the milk is still good is to smell it
"Apparently, in the United States, every state has different laws on milk dates. Therefore, it's really up to people to judge the quality of it. Experts say that if you keep your fridge closer to 34℉, instead of the standard 40℉, you can get an extra week out of your milk. Of course, the longer its container was kept sealed, the better. All in all, it's always best to trust your good ole nose and just smell the stuff."