We're talking about your claim that dishwashing detergent caused your customer's car to fade.
Dawn might have tendancy to strip some LSPs, but there’s not 1 documented case that Dishwashing Soap (or any other soap used to wash cars) will damage paint, trim, rubber or plastic like you originally stated happened to your customer’s car. What you do see is a bunch of people with opinions based on folklore and false perception making biased judgements based on other less informed people. Until I see proof that damage could result using Dawn, I will chose to remain open minded with its use. As it has been said many times here before, the PH value & MSDS ingredients are on par with many car wash soaps that are “paint safe�, yet because Dawn is marketed to clean dishes people run for the hills when discussed. I haven’t noticed any of my plastic dishes detiorating or fading from an even higher concentration of Dawn/Palmolive & hot water combo. In retrospect, the chemicals used at every Automatic, Self-Serve & Touchless Car Wash are much stronger than Dawn and there’s no mass exodus of people(in any state including Oregon) complaining that their paint & trim is fading from it. And more fuel to add to the fire; how about all the Alkaline wheels cleaners used on clearcoated wheels over the last several decades. Don’t see everyone’s wheels fading; and they’re exposed to high heat too. If Dawn (which is much gentler than the soap used at conventional car washes) is supposedly able to damage your vehicle, why aren’t 99% of the vehicles on the road already destroyed?
As far as the test on my car, it’s multi-faceted actually. Half of the entire car is coated with Opti-Coat. Including the paint, chrome/textured trim, wheels, rubber trim and glass. It’s getting weekly washes with Dawn in addition to monthly trips to the Touchless wash. The hood has been completed sanded flat in hopes of accelerating the damaging folklore/claims of UV exposure & Dawn usage. This will not only test the strength/longevity of Opti-Coat, but will also accelerate the supposed claim that Dawn can damage your car on either the coated or bare ½.