I just found this great recipe on how to make your own washer fluid very simple.
All you need is:
- 4 litres of water (if you can get some demineralized water it would be good)
- 1-2 tbsp. of dish soap
- 1 tbsp. of ammonia 8% (or 1 tsp. of 3-fold ammonia)
- 1 litre of methylated spirits or isopropyl alcohol
- 1 splash of citric acid or slightly less eddikesyr
It is better to mix the ingredients outside due to the ammonia being quite harsh to inhale. Mix the water, methylated spirits, ammonia and citric acid and stir gently. Add the dish soap as the last ingredient. Stir very carefully. The soap should be mixed in, but not too much foam.
This mixture will be fine for approximately -9 degrees.
If you need it be useful in lower temperatures add more methylated spirits:
10 % methylated spirits = Frost protection to - 4 degrees
20 % methylated spirits = Frost protection for - 9 degrees
30 % methylated spirits = Frost protection to - 15 degrees
40 % methylated spirits = Frost protection to - 23 degrees
50 % methylated spirits = Frost protection to - 32 degrees
Beware that some types of methylated spirits can react with some types of plastic. Do a test on your windshield wipers to make sure there’s no problem. If you use isopropyl alcohol it can react with some types of varnish. So make sure your car doesn’t react and go for it!
Good luck and have fun!