Source: It says in Bava Basra (91b) that old is always better [than new], except for dates, beer and fish oil.

Explanation: [The Mishnah says that he may give to him its dregs, i.e. if] he informs him. One might have thought that even so it is forbidden, lest [the buyer] swindle others [not tell them that dregs are mixed in].

Assertion: The text says Rava, for the way he mixed wine was different, like it says in Nedarim (55a) and Eruvin (54a) "this [wine] is mixed like Rava brei d'Rav Yosef bar Chama mixes!"

Support #1: Rava said in Shabbos (77a) "any wine that cannot tolerate dilution with three measures of water for each measure [of wine, and it is still proper to drink,] is not [proper] wine."

In Sanhedrin (37a) it says "Al Yechsar ha'Mazeg" - if some of [the Great Sanhedrin] needed to leave, if 23 (just less than a third) remain, corresponding to a small Sanhedrin, they may leave. If not, they may not leave.

Inference: [Normal] mixing is two measures [of water] for each measure [of wine], for the verse discusses the way Stam people mix.

Question: There it connotes that Rava holds that this (three times as much as water as wine) is the primary mixing, for he establishes our Mishnah of mixing two measures of water per measure of wine to discuss only Sharoni wine, which is weak!

Answer #1: Rava establishes the mixing of the verse "Al Yechsar ha'Mazeg" to discuss Sharoni wine.

Answer #2 (Rav Menachem of Yuni): "Al Yechsar ha'Mazeg" means that 50 may not be lacking from the Great Sanhedrin, like the Gemara of "Mazeg". However, if 49 are missing, 22 remain, and we cannot have a Beis Din with an even number of judges, so we add one, and there are 23. (We do not expound the verse based on how people mix wine.)

Question: The Yerushalmi connotes that it literally discusses how wine is mixed.

Explanation #1 (Rashi): The value of 100 Perutos was a Ma'ah, i.e. a sixth of a Dinar.

Question: How could Perutos become so cheap? The average price is 32 in a Ma'ah!

A Ma'ah is two Pundiyonim, and a Pundiyon is two Isarim, and an Isar is [normally] eight Perutos, so [it turns out that a Ma'ah is] 32 Perutos.

Explanation #2 (Rivan): There are 100 Ma'os in a sixth of a Maneh (a Maneh is 25 Sela'im, which equal 100 Dinarim), which is four Sela'im and four Ma'os.

Explanation #3: There are 100 Isarim in a sixth of a gold Dinar (a gold Dinar is 25 silver Dinarim), which is four silver Dinarim and a Ma'ah.

Question: Why did the Torah use a different expression? It should have written Kaspecha Lo Siten b'Neshech uv'Neshech Lo Siten Achlecha!

Answer: Since we need two Lavin, it is normal for the verse to write a different expression. This is nicer.

Question: First we should expound Ribis of money, which we learn from "Neshech Kesef" written first [in the verse]!

Answer: [We ask first about Neshech Ochel, because] Neshech Ochel is written explicitly, and Ribis Kesef we learn only Im Eino Inyan (if it need not teach about itself, we expound a different law from it).