well you want a silicone lubricant, not just plain silicone. id say go you a local hardware store and ask them if they have any silicone lubricant or grease, if they lead you to a caulking type compound (like the compound would use when sealing a window on your house) tell them to go F themselves cause that would be BAD in a window situation.
how come the windows stick so much. i use wd40 for mine. it works for like 3 days and then i have got to put more on.
pulling out the rubber piece and probably try in the near future to clean the rubber and the window and put like baby powder on it. When a new car comes out the rubber feels smooth and almost silky like baby powder. so im thinking its worth a try. If someone trys before me let me know.