Used this stuff for almost 20 years. Easy on, lasts about 6 months with weekly (hand) washing. Also great on headlight and tail light lenses (every two weeks to prevent clouding, and it works).
Paint on my '01 Marquis was like new when I sold the car in '14. Doubly impressive because it was factory silver paint- notorious for fading and clearcoat delamination. Vehicles get washed weekly, rain or shine, with a squirt of Palmolive in a bucket of cold water.