Here's a picture of the factory black plastic bed rail protector on my tow vehicle. I accidentally got some wax on it and was kicking myself thinking (based on past experience) that it would never come off. I taped off a section (on the right) and rubbed the left hand side of the white mark (now clean) with the magic eraser. If you look closesly you can see that in addition to removing the wax, it actually rejuvenated or darkened the plastic a little as well. I'll tape it off next time I'm using my PC 7424, but it's nice to know you can solve these problems with almost no elbow grease, and no greasy temporary liquid covering products that will wear off and reveal the white mess from waxing carelessly.