DIY Car Wash Soap

Steps

1. Fill a large bucket with 2 gallons of warm water.
2. Add 2 tablespoons of liquid castile soap and stir gently to create suds.
3. Add 1 tablespoon of white vinegar and 1 teaspoon of vegetable glycerin. Stir to combine.
4. Rinse the entire car with plain water to remove loose dirt and grit.
5. Wash one panel at a time with a wash mitt, starting from the roof and working down.
6. Rinse each panel with clean water before moving to the next.
7. Give the entire car a final rinse.
8. Dry immediately with a microfiber drying towel.

Why It Works

Castile soap has a mildly alkaline pH (8 to 9), gentle enough to clean road grime without stripping wax or sealant. Dish soaps (pH 9 to 11) contain degreasers that strip wax on contact. Vegetable glycerin lubricates the wash mitt against the paint, reducing swirl marks. Vinegar counteracts hard-water alkalinity, preventing mineral deposits as the car dries.

Alternative

• For heavily soiled vehicles, increase castile soap to 3 tablespoons and add 1 tablespoon of dissolved baking soda for mild abrasive action on bug residue and tree sap.
• For a waterless wash, mix 1 tablespoon of castile soap with 2 cups of distilled water in a spray bottle. Spray one panel, wait 30 seconds, and wipe. Only suitable for lightly dusty cars.

Tips

• Never use dish soap to wash your car. It strips wax and degrades clear coat.
• Use the two-bucket method: soapy water in one, plain rinse water in the other. Rinse the mitt in clean water before redipping.
• Wash wheels and tires last with a separate mitt. Brake dust contaminates your paint wash mitt.
• Wash in shade or when the body is cool. Hot surfaces evaporate water before you can rinse, leaving spots.