for years i poured the left over oil into a cup, with the wicks and threw it into the erev pesach fire.
this year i saw that you should burn it on the 8th day of chanuka as a shmira.
being i never pass up on a segulah, i pored the oil into a frying pan, lined all the wicks up on the side, put pan on slant, so the oil drains towards wicks, lit. to my surprise and excitement every last drop was burned, even the wicks were left to ashes.