Methanol....I buy it by the 200litre barrels for making biodiesel and I have tried it using 2.5, 5.0, 7.5 , 10, 15 & 20% mixes and even down to -12 or was it -13...anyway the 10% mix was fine...but lesser mixes did suffer with freezing to various degree's...
Just contact a chemical dealer....and they'll deliver you a few hundred litres in a jiffy...
Cheers
Dave.