What good value screenwash for the winter?

[MUDGUTZ]

...This subject comes up every year. Every motoring website has a similar thread. I have seen lots of overpriced screen wash for sale everywhere from Halfords to Tesco & various filling stations.

The only ready-mixed screen wash that seems to be good value is the stuff from Lidl: If you can get it. Alternatively you can mix your own.

The information below will hopefully help those who are prepared to help themselves.

I have read over & over again that German screen wash products are very good, so that’s either the ready-mixed type in small bottles from Porsche or VAG or the concentrated type that has a vessel at the top to measure the required quantity. Two appear to be very good value:

Sonax

Einszett Kristallklar

Either product works out about 30 pence per litre when mixed with water which is fine for summer use.
When it comes to winter, all you have to do, when you mix up a load in your 5 litre container, is add some Ethanol / IPA / Isopropyl Alcohol / Isopropanol (Chemists will explain the difference, I’m pretty sure for the purpose of screen wash they are all fine). See below for suitable concentrations.

I got mine from eBay & it worked out about £2.50 per litre, so even at 40% concentration, when combined with Sonax Clear View or Einszett Kristall Klar it’s around £1.30 per Litre. That would be good down to -23 oC

10% Ethanol = Freezing point of -4 oC
20% Ethanol = Freezing point of -9 oC
30% Ethanol = Freezing point of -15 oC
40% Ethanol = Freezing point of -23 oC
50% Ethanol = Freezing point of -32 oC
60% Ethanol = Freezing point of -37 oC

I hope this info helps folk avoid paying excessive amounts for that blue water...