To further prove my point about the car washes or the use of detergents, professional car detailers (PDR Technicians) will use detergents to specifically remove the wax or polish because they want to strip it down to the clearcoat so that there is no foggy buildup or lumps. So if they are using it to remove the waxes on purpose, then it’s counterintuitive to think that it’s okay to use detergents if you don’t intend to follow it up with a good wax or polish.
So hopefully I have driven it home, this idea of not using a detergent. Just to be sure, you don’t want to use a detergent unless your intention is to wax or polish your vehicle right after the wash. These waxes or polishes do more than just make your vehicle look good, they also serve as a protective coat that deflects debris while driving. It could be debris such as stones which might otherwise chip the finish. It also resists scuffing by somebody rubbing up against it in a parking lot. You can compare it to your kitchens floor. When you put a good wax down and drag a chair across the floor, your floor will not be scratched up. If you have no wax on that same floor and drag the same chair across it you will scratch the floor. The same is said for your car. If you drag something across the un-waxed car, it will scratch the paint. These are just the simple truths.
To wash clearcoats there are several types of washes that you can use. These will all be in liquid form Read Full Report. You never want to use a powder form of any of these washes, no matter what the label says. These tend to not dissolve in the water and the hardened undissolved granules or chunks will scratch your vehicle because they have become an abrasive.