Why Are You Not Supposed to Use Dish Soap To Wash A Car?

[dougaross]

Probably for the same reason they tell you not use it on glass. It certainly is not going to damage the glass. It probably just gives unsatisfactory results

[Y2KSVT]

So then why does Dawn specifically say NOT to use it for car washing on their web site?

More than likely the same reason McDonald's has to put a label on their coffee telling you it's hot, why the cleaning people have to put down "wet floor" signs after they mop, and why medicine boxes tell you not to exceed the recommended dosage. Sure, to the normal, sane, non-sue-happy human being, these things are obvious, but there's always one idiot that wants to take advantage of the company that produces the product they used incorrectly. Dawn knows that their soap will strip wax from a car, so they don't want someone trying to get a free paint job because their car's paint looks so bad, even though they waxed it every month, which was just removed with the next washing with Dawn.

Mark