In the stores these days, there are myriad varieties of candles and oils to use for Chanukah lights. However, it is clear that the choicest way to fulfill the mitzvah of lighting the menorah is to use olive oil. The miracle symbolized by lighting the menorah is that olive oil that should have lasted only one day lasted eight. Therefore, it is most appropriate to use olive oil for Chanukah lights.
Indeed, the Maharal of Prague was of the opinion that while any oil can be used, wax candles should not be used at all. Wax candles are so dissimilar to the menorah lights in the Beis HaMikdash that they do not properly reflect the miracle. The halachah is not in accordance with this opinion. Wax candles or any oil may be used. Still, it is most preferable to light with olive oil.
An interesting question was raised about wicks that are wax-coated to facilitate easy lighting. When one lights these wicks, the wax burns before the oil. Can one still observe the hiddur mitzvah of using oil for the lights with wax-coated wicks? Rav Shlomo Zalman, zt’l, answered in the affirmative. The wax burns off rather quickly and the olive oil begins to burn soon thereafter. In essence, the individual is using olive oil, just with a little help from the wax.
Is it preferable to light earlier with wax candles or to wait and light later with oil candles? Rav Shmuel Kamenetsky, shlita, answered that it is better to light immediately with wax candles. Although it is a hiddur mitzvah to use olive oil, performing the mitzvah at the earliest opportunity is also a hiddur. There is another issue that comes into play as well. In the times of the Gemara, people lit their menorahs outside. According to one answer in the Gemara, the mitzvah to light the menorah only lasts as long as people are still walking around in the streets.
The Rema writes that (outside of Israel) one can light even after the streets are empty. The Mishnah Berurah writes that one can light as long as there are still people awake in his household. He could even wake them up for this purpose. If everyone is asleep, he should light Chanukah lights without reciting a berachah. However, the Rema advises us to try and be stringent and not follow this lenient opinion. We should strive to light when there are still people walking around outside. Since it is not clear when this time ends, one should attempt to light his Chanukah lights at the first possible opportunity.
Suppose one set up his menorah with wax candles because he did not have oil available. He is about to recite the berachah when a delivery comes with the oil that he ordered. Should he now remove the wax candles and light with oil instead, or should he recite the berachah and continue with the wax? The Shvus Yaakov says that since the menorah was already set up with wax candles that were designated for the mitzvah, it would be a disgrace to remove them. He should continue lighting with wax. The Chacham Tzvi disagreed, based on a halachah quoted in Menachos (101b), among other reasons. Rebbe Shimon said that even if a Parah Adumah had already been slaughtered, they could redeem it and replace it if they find a nicer specimen. According to the Shvus Yaakov it should be considered a disgrace to replace a Parah Adumah that was already slaughtered for the mitzvah even with a choicer one.
The Shvus Yaakov himself responded that no proof can be deduced from the Parah Adumah. Beis din virtually stipulates that the Parah Adumah is only being used if they do not find a better one. However, here the individual fully expected to fulfill the mitzvah with wax candles and did not make a stipulation. The Shaarei Teshuvah, however, objected to the Shvus Yaakov as well. He says if we would hold of the Shvus Yaakov’s reasoning, then it should apply to other mitzvos as well. Suppose someone is about to recite a berachah over a grossly inferior set of arba’ah minim. Suddenly, his friend appears with a gorgeous and mehudar set. Do we tell the individual that it is too bad on him, and that since he picked up the inferior set first, he must use that for the mitzvah? The Shaarei Teshuvah says such reasoning is beyond the pale. He notes that even the Shvus Yaakov himself seemed to have softened his position. Originally, he wrote that the individual must use the wax candles that were in his menorah first. In the second volume, the Shvus Yaakov wrote that the individual may choose to continue with the wax; he is not obligated to switch to the superior olive oil.
Still, even the Shaarei Teshuvah concedes that once one began reciting the blessing over wax candles, he should light those. This is true even if the oil may be used without any delay. At this point in the game it is too late to switch, and he can only wax poetic about the lost opportunity to light with oil.