Isopropinol (sp)

isopropanol

Actually, any of the simpler (read thin liquid; the higher alcohols are
pastes and waxes) should do to lower freezingpoint, including methanol and
ethanol, propanol, butanol. But as far as I'm aware only the 2 simplest,
methanol (CH3OH) and ethanol (C2H5OH) are made in vast quantities.