Put on winter tires, charge the battery, add a scraper to the car, check the coolant and you’re ready for winter, or not? And what about that summer washer fluid you have left in the container? Can it be mixed with winter?

Foto: Shutterstock/ godi photo

Do you have summer washer fluid left in the container and winter is approaching? What with this? We will advise!

This is exactly the dilemma many drivers go through, especially at times when outdoor thermometers start to show suspiciously low numbers. Although the summer mixture is usually usable down to −5 °C, its main purpose is not to freeze.

Basic summer liquids are intended primarily for degreasing glass, especially from insects. In addition, premium blends contain nanoparticles and more surfactants (detergents that facilitate the dissolution and removal of dirt) for easier grease/insect removal, but also substances that cause the effect of liquid wipers. On the other hand, winter mixtures do not particularly deal with insects and their mission is not to freeze.

So summer and winter mix can usually be safely mixedbut there is a big one ATTENTION! It is not possible to answer the question exactly how much the freezing threshold temperature changes with mixing.

Foto: Shutterstock / BigTunaOnline

Summer and winter mixture can (usually) be safely mixed, just watch out for the change in freezing temperature.

On the one hand, it depends on the residual volume of the summer mixture in the tank and its freezing level, as well as the freezing level of the topped-up winter mixture. Also, the rule does not apply that if I have a liter of summer mixture with a freezing point of 0 °C, mixing it with a liter of a winter mixture with a freezing point of −20 °C will result in a mix of mixtures with a freezing point of −10 °C. Anyway, it will be a little less.

Therefore, if you are going to mix the summer and winter mixture, get the winter one with a higher freezing point, optimally −30 °C and beyond. If you don’t want to mix, then either spray the summer mixture or e.g. suck it out of the container.

Photo: Škoda Auto

After topping up the liquid, don’t forget to get the mixture into the washer system.

As soon as you add fresh winter washer fluid or make a mixture with a dominance of the winter component, get behind the wheel and start washing. Why? The fresh filling must get into the hoses and then into the washer nozzles (sometimes they are heated), so don’t forget to properly spray not only the windshield, but especially the rear glass, where the hoses lead through the entire interior.

And be really thorough, otherwise there is a risk of the liquid in the tubes freezing, which can lead to their damage and result in an unpleasant situation where, as a driver, instead of washing the rear window, you will dispense liquid into the interior or the trunk.

If your car is equipped with headlight washers, which themselves are big guzzlers of liquid, you have to get the winter mixture into this system as well by repeatedly activating the headlight cleaning. Once you are sure that there is fresh filling everywhere, only then fill the container to the brim.

Why does winter washer fluid smell?

How many times does it happen that you buy a winter washer mixture, but after pouring it into the container and applying it to the glass for the first time, you find out that it actually smells. What is the cause of this phenomenon, which appears especially in cheap winter mixes?

  • poor quality alcohol
  • poorly chosen fragrance
  • the fragrance may not be contained in the washer at all (or there is not enough of it)

When does the winter mixture (not) work?

If we leave out the various additional functions of winter washing compounds such as fragrance, it is necessary to focus on the main characteristic, i.e. the temperature at which the mixture does not freeze.

So you usually reach for the liquid that has a resistance of up to -20 °C, because there is rarely more frost and it is enough for a full washer tank and filled hoses. You’re right, that’s enough, but what if the car is moving and you activate the washers? Then comes a sudden change in the rules.

Photo: Jakub Deml

Winter compound down to −20 °C may not always be enough, especially if you drive fast.

Thanks to the company DF Partner, which is a manufacturer of car cosmetics including Sheron windshield washer compounds, we were able to obtain some of the information listed above, as well as a general temperature chart that takes into account the speed of the vehicle, the temperature of the outside air and the temperature of the surface of the windshield, around which the ubiquitous cold air constantly flows .

You probably already know where we’re going with this. In addition, after spraying, the liquid is divided into smaller states that tend to freeze more easily.

Photo: DF Partners

The temperature table also shows the effect of driving speed on the temperature of the glass.

If you look at the table, it clearly shows that if the outside air temperature is zero and you drive at a speed of 50 km/h, your windshield has a temperature of −9 °C from the outside. If you drive it in the district at 90 km/h with an outside air temperature of −10 °C, you are already at a value of −25 °C within the front window. And that’s when classic mixtures down to −20 °C applied to glass stop working.

And the same applies to highways, when, for example, at −5 °C at 130 km/h, your front window has a temperature of about −19 °C, while if the air temperature drops to −10 °C, the windshield already has to be washed with by freezing −26 °C. As soon as the ambient air temperature is around −20 °C, even winter washer fluid with a freezing temperature of −30 °C will not help you much while driving.

Photo: Tomáš Kopečný

If the temperature on the surface of the windshield is too low, the applied liquid may freeze.

However, we would like to point out again that these are indicative values, which in practice can also be affected by, for example, the force of the wind, rain or, conversely, the action of the sun’s rays.

You still have a few days to solve the issue of the winter mixture, but don’t hesitate too long, because winter is already knocking on the door like the annual increase in the price of liability insurance. And when you choose that winter liquid somewhere in a store or gas station, always check the freezing temperature on the package, which should be at least −20 °C, but preferably −30 °C or better.