If on Friday night one made Kiddush using a cup that holds 2.9 or 3 oz., even though it is preferable to use 4 or so oz. on Friday night, is he still yotzi, or should he repeat Kiddush?
He is yotze with this amount. In fact this is the amount that R’ Chaim Naeh, says is the amount of wine that is needed for kiddush. (86cc which equals 2.9 fl ounces), and you should not say kiddush over again.