never used screenwash. 
what quantity do you put in the bucket?
Last year during the two prolonged dumpings of snow we had here with temps below freezing, for commercial work (shops, etc,), I used the cheapest screen wash diluted one part screenwash to two parts water. It worked fine under the circumstances and got the muck/dirt off but I don't rate it as a decent window cleaner though as it has detergent in it but I was at least still keeping the pennies coming in.
