You need a protectant with a bit more cleaner in it... try the brand new meguiars protectant, that is in the bottle that looks like their new wax, the nxt stuff...

This stuff works well, and only seems to attack oxidized rubber, I believe they also recommend it for wax that has got on rubber trim..

Greg

(my favorite for this is Black Chrome, by Turtle Wax, but it is discontinued, and I only have 6 bottles left)