Q. Can you use oil for Chanuka lighting that was left uncovered overnight?
Horav Shlomo Miller's Shlit'a opinion is that it is permitted for a number of reasons. Firstly Poskim disagree whether in our days we should discard certain liquids that were left uncovered or Mashkim Megulim. The main reason for their prohibition is the possibility of their contamination by poisonous snakes (Avoda Zara 30a, Chulin 9b) and since that rarely occurs in our populated cities, we are lenient (Shulchan Aruch Y.D. 116:1, Mishna Berura 160: 23.) However, some Poskim do remain stringent (Pri Chodosh and Pri Toar, quoted by Birkei Yosef and Aruch ha-Shulchan Y.D. 116:1.) It is important to know that when Mashkim Megulim are prohibited they are even when left uncovered and unsupervised for a short time, not only overnight.
Poskim also differ if prohibited or non-kosher oil can be used for Chanuka lights and many are lenient (Sdei Chemed – M. Chanuka 14, Kaf Hachaim 673: 11, Beis Shlomo O.H. 10: 108).
However the main reason that oil left uncovered is undoubtedly permitted is that there is no Mashkim Megulim issue on oil, since snakes don't drink from it (Chulin 49b, Bais Yosef Y.D. 116, Yemei Chanuka p. 71)
Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit"a
Important Numbers
