Optimum No Rinse is my cleaner on everything. Of course it's a dedicated car wash solution for a particular purpose; to get your outside clean without rinsing, while adding some surface "slicker" to make getting it clean easier. As a glass cleaner it works well too. Since distilled water is my first "go to" as a cleaner, having ONR in the spray bottle solution is just a bonus. When this won't touch a spot, I get out the isopropyl alcohol. That solves just about everything. I'll use elbow grease and more alcohol before resorting to a strong chemical. So far, I haven't had any emergency cleaning incidents. On my latest road trip, I picked up a few dark brown specks, who knows what, from what? The alcohol worked; I just had to be insistent. They were really stubborn.