No, you should not use washing-up liquid to clean your car's windscreen. While it might seem like a handy and effective cleaner, the chemical makeup of dish soap is fundamentally incompatible with automotive glass and related components. These products are designed to cut through grease on dishes, not to be gentle on the specialized coatings and materials found on your car. Using them can lead to significant and often expensive problems over time.
The primary issue lies in the ingredients. Washing-up liquids contain surfactants (surface-active agents) and degreasers that are too harsh for automotive surfaces. Your windscreen has a hydrophobic coating—either applied by the manufacturer or as part of a aftermarket treatment like Rain-X—that helps water bead up and roll off for better visibility. Dish soap will systematically strip this coating away, leaving a streaky, water-sheeting surface that is harder to see through in rain. Furthermore, many dish soaps contain salts and additives that can damage the rubber seals and trim around the windscreen, causing them to dry out, crack, and deteriorate prematurely.
For safe and effective cleaning, always use a cleaning solution specifically formulated for automotive glass. These products are pH-balanced to clean without damaging the glass or its surroundings. The best practice is a two-step process:
- Pre-Clean: Use a dedicated automotive glass cleaner or an isopropyl alcohol and water solution (mixed 1:1) to dissolve stubborn grime, tree sap, and bugs.
- Final Wipe: Follow up with a clean, damp microfiber cloth to remove any residue. Using a high-quality microfiber towel is crucial as it traps dirt without scratching the surface.
| Cleaning Agent | Primary Use | Effect on Windscreen Coating | Effect on Rubber Seals | Overall Recommendation |
|---|
| Washing-Up Liquid | Cutting grease on dishes | Strips hydrophobic layer | Dries out, causes cracking | Avoid completely |
| Automotive Glass Cleaner | Cleaning auto glass | Safe for most coatings | Safe, often contains protectants | Highly Recommended |
| Isopropyl Alcohol (50/50 Mix) | Dissolving sap, bugs | Can degrade some coatings with frequent use | Can be drying if overused | Good for occasional heavy cleaning |
| Vinegar & Water Solution | Removing hard water spots | Generally safe | Can be acidic over time | Acceptable for spot cleaning |
| Plain Water | Rinsing loose dirt | No effect | No effect | Not sufficient for proper cleaning |
