To make iso or methanol truley effective...sub 1% dilutions are a complete waste of time...
During the really cold weather we had with temps around -12 deg at night I trialled various mixes of methanol ranging from 1% to 20% (all mixes were in coke bottles of a litre).
I have also tried a 7.5% mix in my tank of 400 litres and the methanol evaporates and then I was left with frozen water on the glass.
So IMHO ....iso and methanol are great in enclosed systems but when out in the open air...pretty much a waste of time and money and as for some claiming it makes the windows shine better..I just cannot see how this works but I am open to hear about your experiances.
I am not a techie by any stretch of the imagination and my tests should be treated with that in mind
Cheers
Dave.