well i have used cheap stuff and for the second year reunning my rear washer stopped working got it repaired under warrenty but was told seat will only do this once a year and was recommended vw screen wash so bought it stupily from the stealers £9 for 1.5 litres to say i was shocked is an undestatement. Considering i then went into lidl and that had 5 litres of stuff that should work to -60 for a fiver. I will say thought that you can notice the difference between the vag stuff and cheaper stuff it comes out the bottle like calpol
Isn't vag stuff super concentrated so you mix it at 10:1 with water for down to a reasonably cole temperature?