Safe, Clean, Streak-Free

• Winter washers ineffective on summer dirt
• Poor vision compromises road safety
• Test seal helps with purchase decision

Insect remains, tree gum, bird droppings and pollen cause a dangerous lubricating film on car windscreens in the warm seasons. According to DEKRA experts, for good visibility from spring on, it is important to pour a special summer windscreen washer, which is effective against typical summer dirt, into the washing water.

"The windscreen washer for winter is designed to provide effective protection against frost and freezing, besides cleaning. By contrast, the summer washer copes better with typical, albuminous summer dirt," explains Thilo Kunst, expert in automotive chemistry at DEKRA. If you fill up with a winter product in summer, expect that the insect remains in particular will not be removed as efficiently and the dirt will smear the windscreen.

In the dark or when the sun is low in the sky, back light can lead to light scattering on the windscreen and impair the driver's visibility. This is often connected with a higher risk of accident. Therefore, in his expert opinion, Kunst recommends carrying a full bottle of windscreen washer in the car and regularly refilling the washing water.

You should keep an eye out when choosing a windscreen washer. Unsuitable products could corrode varnish and rubber seals or cause stress cracks on the headlights. That is why it is recommended to buy a product with the test seal. With this, the customer can be certain that all significant aspects have been checked, from cleaning performance and material compatibility to tests for harmful ingredients.

Whether the driver prefers a pre-made mix or a concentrate is a question of convenience and price. The convenient pre-made mix costs more. With the cheaper concentrate with mix ratios up to 1:100, a compact 250 ml bottle produces approximately 25 l of cleaning solution.

However, drivers cannot always rely on the cleaning performance of cleaner, wiper and water. "If insect remains are caked on the windscreen after longer journeys on the highway, then often only a sponge and elbow grease will help," says Kunst, an expert from the DEKRA laboratory for environmental and product analysis. In addition, for clear visibility in spring, it is recommended to check wiper blades for tears and dirt and to change them if necessary. Furthermore, the water nozzle should be correctly positioned and the windscreen should be regularly cleaned from the inside.