Is there a reliable method of preventing the windscreen washers from freezing? I have the genuine washer fluid mix but that stops working at 0oC and doesn't free up for two hours back in the low country. Surely this is a known problem in Colorado or Canada.

Check the bottle for your "genuine washer fluid". Manufacturers do make a "warm climate" mix that is only good at and above freezing. It should be clearly marked on the bottle.

Put a cup full of your stuff in your kitchen freezer and see if it also freezes. If it does then you've got the wrong stuff.

Another thought...the fluid might not be the problem. You didn't say if the fluid won't squirt at all, or if it freezes on the windshield after it squirts. It could be that the sprayer nozzle is clogged with freezing environmental water. Not sure how to address this issue. Hopefully someone else has an answer.

Thanks for your comments. I shall check with the dealer as to the fluid rating.

And I presume it is freezing around the nozzle. When I push the button, I hear the pump running but there's nothing coming out to the screen.

It's only been -6oC overnight, and about zero in the day so I doubt the washer bottle itself froze.

Mine has been as low as -25F overnight and never had the windshield washers freeze. The HEADLAMP washers on the other hand drive me nuts with freeze ups if I don't use fluid rated to -35F. I now run this fluid year round.