Since you probably can't hurt anything by trying this, grab a piece of fine grain sandpaper, stick it between the window and the door seal and lightly move the sandpaper right to left. The surface of the seal is too smooth so it's like gym shoes on a shiny gym floor - remember how they squeak in a basketball court? If you scuff up the rubber surface, the problem should go away if it's coming from the seal. And you won't need new seals!

Sent from my iPad using Tapatalk HD