An animal olah (burnt offering) and a shelamim (peace offering) korban (offering) have nesachim (libations) brought with them: a Mincha (meal offering) of flour and olive oil. It is burned fully on the Mizbeach (altar), and yayin, which is poured on the Mizbeach, is wine. A person could also donate wine as an independent korban without an accompanying animal.
Here we'll talk about somebody who made a vow but forgot exactly the specifics of it. The Mishnah says, “If somebody says, ‘I'm taking upon myself to bring wine to pour onto the Mizbeach,’ but he didn't specify how much wine he was going to bring, he has to bring a minimum of three lugin (log measures) of wine,” which is the smallest amount of wine mentioned as nesachim in the Torah. The smallest amount of wine brought is one-fourth of a hin (liquid measure), which is three lugin, and it is brought with a lamb offering. So if a person makes a vow to bring wine, this would be the minimum amount he has to bring.
Shemen, lo yifchot mi-log (at least a log of oil): if he makes a declaration, swearing that he accepts upon himself to bring oil, he has to bring at least a log of oil, which is the smallest amount of oil brought with a voluntary Mincha. Rabbi says it has to be at least three lugin of oil, which is the smallest amount of oil brought as nesachim together with an animal offering. According to Rabbi, the minimum amount of oil is learned from the wine nesachim. We just said that with wine nesachim, the minimum is three lugin. So he would compare it as well to the oil.
When somebody says, “I made a vow to bring a specific amount of lugin, but I don't remember what number I specified,” he has to bring an amount equal to the amount brought on the day with the greatest amount of wine and oil nesachim. That is the first day of Sukkot (Festival of Booths), when it falls on Shabbat, when a total of 140 lugin of wine and oil are brought. According to the way we learned it from there, on the first day of Sukkot, when it falls on Shabbat, more oil and wine are offered than on any other day of the year because of the offerings of the holiday, the Musaf offerings, the Shabbat offerings, and the regular Tamid offerings. Each one of them is brought with nesachim, and all of those equal a total of 140 lugin. Therefore, this person has to bring 140 lugin of wine or oil to fulfill his vow, because we make the assumption that he didn't vow to bring more than the public ever brings on an individual day. So he has to bring that number, but he wouldn't have to bring more than that. We're not going to make the assumption that he would ever bring more than the kahal (public) brings on a specific day.