Ultimate Speed Screen wash from Lidl 5lt £5.99, neat -60C, 1:1 -20C, 1:2 -10C
Read the instructions. If you are wanting frost protection then beware of mixing too much water.
That goes for the VW screen wash as well. Adding water greatly reduces the frost protection. If you peel the label back it gives instructions for mixing.
When you add 50% water to screen wash it does not reduce the frost protection by 50%. It usually reduces it by 66%.
When you add 2/3 or 66% water - it reduces frost protection by around 85%.
I once had the VW service manager tell me that they had put half a litre of screen wash in the car and left the rest in the bottle for me. He then said the screen wash was mixed 50/50

AFAIK there are high capacity 5ltr (or is it 4.5ltr) water bottles in both our cars because of the headlight washers.

So the mix was probably 1:9 or just 10% screen wash, with minimal frost protection.
