This requires a (slightly) conductive fluid, but most common windshield washer fluid mixtures will work. Many cars display a warning when the fluid level is low, and some car makers have replaced the float sensor generating this signal with a simple two-pin probe in the tank. Fluids are now usually based on ethanol, often with small quantities of isopropanol, ethylene glycol, and Butanone. As of, methanol was banned from use in windscreen washing and defrosting products in the European Union. Methanol vapor is harmful when breathed in, and methanol poisoning presents a risk of death, severe ocular toxicity, and other severe effects if ingested. ДЄnti-freeze, or methylated spirits, may be added to a mixture to give the product a lower freezing temperature. Distilled or deionised water is the preferred diluent, since it will not leave trace mineral deposits on the glass. It is sometimes sold as sachet of crystals, which is also diluted with water. Dilution factors will vary depending on season, for example in winter, the dilution factor may be 1:1, whereas during summer the dilution factor may be 1:10. The most common washer fluid solutions are given labels such as 'All-Season', 'Bug Remover', or 'De-icer', and usually are a combination of solvents with a detergent. Windshield washer fluid is sold in many formulations, some are pre-mixed and others require dilution before use. Many other manufacturers have employed electrically heated washer nozzles primarily to prevent them from freezing closed, not in an attempt to heat the fluid itself.

Mercedes Benz has used a thermostatically controlled heating element, with the engine coolant as the heat source, since the mid 1980s on certain models. The company halted the production of these mechanisms after they found that it was prone to start engine fires. GM also claims heated washer fluid helps in removing bug splatters and other road accumulation. The system emits a fine mist of heated water that clears frost without damaging the windshield itself. For example, General Motors had begun equipping vehicles with heated washer fluid systems from the factory beginning in 2006 with the Buick Lucerne sedan. Although there are a few aftermarket preheat devices available, many automobile makers offer this feature factory installed on at least some of their vehicles. This is especially desirable in colder climates when a thin layer of ice or frost accumulates on the windshield's surface, as it eliminates the need to manually scrape the windshield or pour warm water on the glass. Washer fluid may sometimes be preheated before being delivered onto the windshield. In 1946 General Motors installed windshield washers on all their vehicles as an extra cost option, while Chrysler offered the feature optionally in 1950 and Ford offered them for 1952. The first windshield cleaner unit offered for automobiles was in 1936, as an aftermarket option to be installed on cars after they were bought. Some vehicles use the same method to clean the rear window or the headlights. The windshield wipers are automatically turned on, cleaning dirt and debris off the windshield.

A control within the car can be operated to spray washer fluid onto the windshield, typically using an electrical pump via jets mounted either beneath the windshield or beneath the wiper blade(s).