FWIW, here is my little tip that I follow without exception. Never leave your paint exposed without a protective coat of some sort on it... If I am not waxing it after a wash, I'll dry it and add a coat of detail spray or spray on wax. Or at least dry it with a wax-as-you-dry type product. This makes consequent maintenance much easier and it keeps the paint looking good and protected ALL OF THE TIME. My point is, don't wash your truck and leave the paint naked.