139:20 The oil that remains in the menorah after Chanukah, as well as the wicks, should be made into a fire and burned. They were put aside to be used for the mitzvah, so it is prohibited to derive benefit from them unless one initially made a condition not to consider whatever remains to be specially designated. (This refers to when one put the proper amount of oil into the menorah but the light went out. If he put surplus oil in, it may be used – Mishnah Brurah 677:18. What’s left in the bottle that was never poured into the menorah is certainly permitted – Bi’ur Halacha 677:4 s.v. hitzrich.)
139:21 All eight days of Chanukah, we recite “Al HaNissim” in Shemoneh Esrei. If one forgot and did not say it, then if he remembered before saying G-d’s Name in the bracha of “HaTov Shimcha…,” he goes back and says Al HaNissim. If he did not remember until after saying G-d’s Name, he finishes the bracha and does not go back.