The short answer
Winter washer fluid contains alcohol to lower its freezing point; summer washer fluid contains more cleaning agents to dissolve insects, pollen and road film. An all-season formula sits between the two. Plain water freezes and does not clean grease or insect residue.
What is in the bottle
| Formula | Main components | Designed for |
|---|---|---|
| Summer | Water, surfactants, solvents for organic residue | Insects, pollen, dust, road film |
| Winter | Water, alcohol (to depress the freezing point), surfactants | Salt spray, slush, frost, sub-zero temperatures |
| All-season | Balanced mix of the two | Year-round use in mild climates |
The concentration of alcohol determines how low the fluid stays liquid. A winter formula rated for a given temperature is only safe down to that temperature when it is used undiluted, or diluted exactly as the label states.
Why not just water
- Water freezes at 0 °C. A frozen reservoir, pump or jet can crack, and a frozen jet leaves you without washing exactly when the windshield is covered in salt.
- Water has no surfactants. It spreads grease and insect residue instead of dissolving them, and the wipers smear it into a film.
Switching between seasons
- In autumn, run the summer fluid down before topping up with winter fluid, so the mixture in the reservoir is strong enough for the first frost.
- Do not mix concentrates from different products without checking the label; some formulas separate or cloud when combined.
- In spring, switch back once night temperatures stay above freezing. A winter formula still cleans, but a summer formula removes insects better.
All VOLTREK washer fluid formulas are developed for compatibility with paint, rubber, plastics and washer jets. Choose the formula for your season and check the label for the temperature rating.