Hilchos Chanukah / Kindling the lights (r) – 25

1. All types of wicks are acceptable for the Chanukah lights, but to fulfill the mitzvah ideally, the wicks should be of cotton or flax (Shulchan andMishnah Berurah 673).

2. Edible oil (i.e., not bitter) that was left under the bed, may not be used for Chanukah lights nor Shabbos lights], since it was affected by a ruach ra’ah(negative spirit). But bitter oil that is not edible at all is not affected by ruach ra’ah and may therefore be used for kindling(Kaf HaChaim ad loc.).