I cannot seem to get more than six months before my rear view mirror falls off the windshield to the floor on my F150. I have used mostly Permatex cement intended for the purpose. I only use a small single drop applied to the metal pad before sticking on the windshield and perform all prep work as indicated in the product directions. I follow the directions to the letter and even wait a couple days before attaching the mirror assembly to the metal mounting pad. I am ready to take it to a windshield shop. I would appreciate any product or application ideas.