Trivia: What car product can be used to prevent soap scum?
Windshield wiper fluid
The correct answer is Car wax
So why is this answer correct? : Soap scum is a white or gray residue that occurs when soap ingredients like calcium stearate and magnesium stearate mix with hard water. Luckily, there are plenty of cleaning products to get rid of this unsightly problem, such as Borax or bleach-based sprays. Applying a gel gloss or car wax after the surface also will make it more difficult for soap scum to return.