I have a 740 with a plastic bumper bar. It is grey and it has faded badly over the years. I have used Autoglym bumpercare on it, and it works very well bringing them back to look like new. However after a couple of weeks or if it rains, the stuff washes off. I was thinking that maybe I could use a clear coating or something on top of the bumper to protect it from the rain. I was wondering if anyone has any ideas or experiences with products??