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Washer fluids
Washer fluids
The correct washer fluid maintains a clear view and protects the washer system. Select it for the season, expected temperatures and vehicle requirements.
Summer and winter fluid – what is the difference?
| Fluid type | Typical composition | Main purpose |
|---|---|---|
| Summer | Water, cleaning surfactants and, depending on the product, solvents and other auxiliary ingredients. | Removing insects, grease and summer dirt. |
| Winter | Water, antifreeze components – usually alcohols such as ethanol or isopropanol – and cleaning additives. | Protection against freezing and removal of salt and winter dirt. |
The exact composition varies by product. Summer fluid and water alone do not provide reliable frost protection.
Preparing for winter: topping up the reservoir is not enough
Prepare the winter fill before the first frost:
- Use up or have the remaining summer fluid extracted; do not run the pump dry.
- Add winter fluid with suitable frost protection.
- Operate the washers briefly to move the winter fluid into the lines and nozzles.
- Remember the rear washer and any headlamp washers.
Remaining water or summer fluid reduces the resulting frost protection, so the value on the added container may not match the actual mixture in the vehicle. The old fill can also remain in the long line to the rear window.
What can freezing damage?
Frozen fluid can damage the reservoir, pump, hoses or their joints and cause a subsequent leak. Expanding ice can also rupture a line.
Repeatedly operating a blocked pump can damage it. On some vehicles the control unit can record a fault and restrict further pump operation.
What should be used for dilution and why follow the ratio?
Dilute concentrate exactly to the table on its container. A 1:1 ratio does not necessarily provide the same frost protection for different products.
Use ready-mixed fluid without further dilution unless the manufacturer expressly permits otherwise. Adding water changes cleaning performance and frost protection.
Select the water type under the instructions of the vehicle and fluid manufacturer. Clean water limits contamination of the system; suitability of hard water also depends on the product formulation.
Distilled or demineralised water is not a universal recommendation for every vehicle. Some Volkswagen manuals expressly do not permit distilled water.
Why prefer summer fluid in summer?
Summer products principally target insects and other summer dirt. Winter fluids have a different formulation, and their antifreeze protection is not needed in warm weather.
A winter fluid suitable for the vehicle is not automatically harmful or prohibited in summer. Some concentrates also have a manufacturer-specified summer dilution. The exact product and its instructions govern.
Fluid rated to −20 °C at an outside temperature of −16 °C
Higher speed alone does not mean such a mixture must freeze. Moving air accelerates cooling but does not by itself cool the fluid below the actual ambient temperature. A small hose diameter does not change the mixture’s freezing point. Fluid in the reservoir behaves differently from a thin film on the glass: evaporation cools the thin film and also changes its composition.
Washer operation can still fail in frost. The actual dilution, residual water and suitability for the exact nozzles matter. Fill frost protection need not equal the temperature limit for correct atomisation by fan nozzles; a manufacturer may state both values separately.
What should you do if the washers freeze?
- Do not operate the washers repeatedly.
- Allow the whole system to thaw gradually in a space above freezing.
- Do not use a heat gun or another intense heat source.
- After thawing, adjust or replace the fill and verify operation and system tightness.