Windscreen washer fluid belongs in the washer reservoir under the bonnet. Use a purpose-made automotive product that meets any requirements in your vehicle’s owner’s manual, then follow the bottle directions for mixing and filling. A premix goes in as supplied; a concentrate must be diluted at the stated ratio.
Do not assume that plain water, household detergent, engine coolant or a homemade recipe is suitable for every car.
What is washer fluid?
Washer fluid is the liquid sprayed onto the windscreen when you operate the washers. The reservoir, pump, hoses and jets deliver it; the wiper blades then sweep the wetted glass.
It is sometimes called windscreen wash, washer liquid or, less accurately, “wiper blade fluid”. It does not lubricate the blades. Its job is to help remove material such as dust, road film and insect residue so the blades can clear the glass more effectively.
Exactly what is in washer fluid depends on the product. The label and safety data sheet are the reliable sources for its ingredients. Some products are ready to use, while others are concentrated; material compatibility and frost protection also differ.
Which windscreen washer fluid should you use?
Start with your owner’s manual. It may specify a type of washer fluid, a performance requirement or restrictions for the vehicle’s washer system. Then choose an automotive windscreen washer product that meets those directions.
Premixed washer fluid
Premix is ready to pour into the reservoir. It is the straightforward option when you do not want to measure a concentrate. Check the label for its intended conditions, including any stated freeze protection.
Washer fluid concentrate
Concentrate must be mixed before use unless its label specifically says otherwise. Use the water type and dilution ratio stated on the bottle. Some products give different ratios for general cleaning, heavy insect contamination or colder weather.
More concentrate is not automatically better. An overly strong mixture falls outside the product maker’s directions and does not guarantee better cleaning. Do not estimate the ratio: measure it, and mix it in a clean container if the label instructs you to do so.
If you do not know what is already in the reservoir, do not assume two products are compatible. Check both labels and the owner’s manual. If the reservoir has been filled with the wrong product or contains sludge, arrange for the system to be drained and cleaned rather than adding another chemical.
What about water-repellent coatings and window tint?
Some vehicle manufacturers warn against washer fluids containing water-repellent or bug-wash additives because those products can cause streaking, smearing or wiper noise on particular vehicles. Treat that as a vehicle-specific restriction rather than a ban that applies to every car: follow your owner’s manual.
Washer fluid is sprayed on the outer windscreen. It is not a cleaner for the cabin side of the glass or for window-tint film. If your windscreen has an aftermarket coating, or tint film is installed on any glass you clean by hand, follow the coating or film maker’s care instructions. Different products have different cleaning requirements, so do not assume one tint or coating rule applies to all of them.
Can you use water instead of washer fluid?
Plain water has limits. It may shift loose dust, but it is generally less effective on oily road film and insects than a suitable washer fluid.
Water can freeze in the reservoir, pump, hoses or jets. That matters for motorists travelling through alpine areas and other parts of Australia that experience sub-zero temperatures, even if the car is usually kept in a warmer region.
If you need an emergency top-up, check what your owner’s manual permits. Do not treat water as a universal long-term substitute, and do not add a random amount of concentrate later without recalculating the mixture.
What should not go in the washer reservoir?
Unless your vehicle manufacturer and the product label specifically permit it, avoid:
- Engine coolant or radiator antifreeze. It is made for the cooling system, not for cleaning the windscreen.
- Dishwashing liquid, hand soap or laundry detergent. These are not formulated or labelled for a washer reservoir and may foam or leave a film.
- Household glass cleaner. A product intended for hand-cleaning glass is not automatically suitable for a vehicle’s reservoir, hoses, paint or trim.
- Methylated spirits or other solvents. Do not improvise a cold-weather or cleaning mix.
- A universal homemade recipe. Vehicles, materials, climates and product concentrations differ, so one mixture cannot be prescribed safely for every car.
Never pour washer fluid into the coolant expansion tank, brake-fluid reservoir or another under-bonnet container. If you are not certain which cap is correct, stop and check the owner’s manual.
How to identify the windscreen washer reservoir
Park on a level surface, apply the parking brake and switch the vehicle off. Open and secure the bonnet according to the owner’s manual. If you have just driven, allow enough time for the engine bay to be safe to work around.
The washer reservoir is usually a translucent plastic tank with a flip-top or screw cap. The cap commonly shows a windscreen with spray above it, but its colour and position vary between vehicles. One reservoir often supplies the front and rear washers, but the layout is vehicle-specific.
Do not rely on cap colour alone. The coolant reservoir can also be translucent, and opening the wrong system—especially when hot—can be dangerous. Use the diagram in the owner’s manual if the washer symbol is not obvious.
How to refill windscreen washer fluid safely
- Read the vehicle and product directions. Confirm whether you have premix or concentrate, the correct dilution, any temperature rating and the recommended fill level.
- Prepare concentrate correctly. Measure it with clean equipment and mix it as directed. Keep dirt, old fluid and other chemicals out of the container.
- Locate the washer reservoir. Check the cap symbol against the owner’s manual before opening it.
- Clean around the cap. Wipe away dust so it cannot fall into the reservoir.
- Check the reservoir and visible hoses. Look for cracks, wet areas or fluid below the vehicle. A reservoir that empties unusually quickly may be leaking.
- Pour slowly. A clean funnel helps with a narrow filler neck. Fill to the marked level or the limit stated in the manual; do not force in extra fluid.
- Refit the cap firmly. Wipe up spills immediately and wash the affected area with water unless the product label specifies another method. Wash your hands after handling the fluid.
- Test the washers while parked. Use a short operation to confirm that fluid reaches the windscreen and the jets are aimed correctly. Avoid repeatedly running the pump with an empty or frozen system.
Store leftover product in its original, labelled container, closed securely and away from children and pets. Follow the storage and disposal directions on the label.
What to do if the washer jets are blocked
Start with simple observations rather than holding the washer control on:
- Check the fluid level. Rule out a low or empty reservoir first.
- Listen for the pump. A hum means the motor is running, but it does not confirm that the pump is producing pressure. Little or no spray can still result from a blockage, disconnected hose, leak or pump fault. Silence may indicate a fuse, switch, wiring or pump fault.
- Compare the jets. One weak jet is more consistent with local dirt or a nozzle problem. Several failed jets can point to a shared hose, frozen fluid, blockage or pump issue.
- Look for escaping fluid. Fluid under the car or inside the engine bay while the pump runs suggests a split or disconnected line.
- Inspect the nozzle openings. Remove surface dirt gently with a soft brush or clean cloth. Only insert a fine tool if the owner’s manual gives that procedure; forcing a pin into a modern jet can alter its spray pattern or damage it.
If the reservoir contains contaminated or gel-like fluid, the system may need to be drained and flushed. Do not try to dissolve the blockage by adding household chemicals.
Book an inspection if the reservoir is full but the washers still do not work after basic checks, the pump makes an unusual noise, a fuse fails again, fluid leaks, or access requires removal of trim. A workshop can test the pump, electrical supply, hoses and jets.
Washer fluid for hot and cold Australian conditions
Choose for the coldest conditions the car will encounter, not only the weather where it is usually parked. Trips to ski fields, alpine roads, inland areas and Tasmania can expose the washer system to frost or freezing temperatures.
Check the product’s stated temperature protection and use its cold-weather dilution exactly. Not every washer fluid contains antifreeze, and a summer dilution may not provide the same protection as a winter one.
Hot conditions do not justify exceeding the concentrate ratio. For long drives through dusty or insect-heavy areas, check the level before leaving and use the product’s heavy-cleaning dilution only if one is listed.
Do not add engine coolant to the washer reservoir. If the system appears frozen, do not keep operating the pump. Let the vehicle and system thaw safely, then check for leaks or damaged components and refill with a suitable product as directed.
When clean fluid does not fix poor wiping
Washer fluid can loosen contamination, but the blades still have to remove it. Clean the windscreen and inspect the rubber for splits, hardening, deformation or material pulling away from the frame. Persistent streaking, smearing, chattering or missed areas after the glass and washer system are clean can indicate worn or unsuitable blades.
Check your blades after refilling washer fluid. Use WiperPro’s vehicle selector to find replacement blades listed for your make and model, compare your options in the best wiper blades in Australia guide, and follow the installation instructions when fitting replacements. More maintenance information is available in the WiperPro guide hub.