Cleaning Convertible Tops

Hello,
I drive a 2000 mustang vrt. (vinyl black top) and it is the bigges pain to clean and protect the top. Does anyone have any tips or products they use? I have a problem with the protectants I use because at the first rain it runs all over my car (can't be good for paint). Can anyone help me?

i work for a classic car museum/shop, and for all of our convertable tops we use Mother's Convertable Top cleaner, it can be purchased at any auto parts store.