The question was asked in Halacha regarding lighting Friday night candles. Which is the best way to light? Is it best to use a wax candle or a certain type of oil? Maran writes in seman 264:6, [listen to the audio clip for the exact quote] after listing different oils that are Kosher, to use for the lighting of Friday night, he concludes that the best way to perform the Mitzvah is by using olive oil.
Mishna Berura explains that olive oil is best because it draws after the wick better than all other types of oils, and therefore it’s a nice oil, and it’s a nice flame, and it won’t come to flicker and thus it prevents the possibility of one coming and playing with the light, which is a problem on Shabbat.
Then the Mishna Berura says, that if you can’t have oil, then other oils come next, and then comes wax candles. The truth is, today, wax candles produce a good f lame and a steady flame, and most of the time they will not flicker. However, the order would still be, olive oil, and then another type of oil, and then the wax candles.
So the question is asked what about cotton oil? Let’s say you have cotton oil and we want to use it, would it be a problem? So first we need to understand why it might be considered in fact a problem. That is because in Bame Madlikin (which we read on Shabbat), it says, ‘BiLo Shemen Kik,’ which means, ‘not with the oil of Kik’. What is ‘Kik’ oil? So Rashi says in Shabbat, that it is referring to the oil of Tzemer Gefen, which is cotton oil. Halacha says from the Mishna that you are not allowed to use this oil.
So Chacham Ben Tzion discusses it and says that today might be a little different with regard to cotton oil. Since cotton oil is purified and its impurities are removed, and it’s processed, so it may be different than the old cotton oil. We see today, that if you put cotton oil and a wick, that it draws nicely. It’s good oil. Therefore Chacham Ben Tzion says if you are going to use cotton oil, mix another oil in it that is Kosher, in order to have at least a Kosher oil in it, and then you could be lenient using it. So this is a case that maybe in the times of the Gemara it was not a good oil for the way they processed it. But since today it is a different process, so long as you mix a drop of another type of oil into it then it becomes kosher and you will not have a problem. For example you pour the cotton oil and then put a drop of olive oil.
We can further rely on the Rambam that explains Shemen Kik as different oil totally, so we have what to rely on so long as we mix the cotton oil with some other Kosher oil.
So again, olive oil takes first precedence, then other types of oil including cotton oil but only if you mix with another Kosher oil, and then we say a wax candle.
