Stunningly good - the best screen wash I've used.
Used neat, it coped with the severest Cumbrian frosts of winter 2018/19. A major plus is nil re-icing after I set off driving. In my experience, cheaper inferior alternatives, often dyed blue, thaw windscreen ice well enough while the car is stationery, only for it to re-ice again as soon as I get underway. Can't recommend Prestone Extreme enough in this regard when used neat - never experienced re-icing of the screen since discovering this product.
Seems to work fine. I've been using a 1 in 10 mix
Seems to work fine. I've been using a 1 in 10 mix and last week when it was below freezing it worked every time. Perfectly clean screen.
Useless
Thought I'd try this screenwash as I'd read good reviews however it was completely useless. Instructions say dilute 1:10 summer. 1:9 autumn and use neat in winter where it works down to -23 celsius. We were expecting a few frosty mornings so I thought I'd go for a half and half mix. The next day, it was literally just -1 celsius and this stuff froze on my windscreen! Absolutely worthless.