do i have to buy an OEM wiper blade insert to get a new wiper blade, or can i buy any wiper blade to replace the wiper blade i currently have? I think it's starting to go, and my friend, who has a bmw 330xi (i know, completely different car) had to buy just the blade insert; he tried a pepboys wiper blade from an aftermarket manufacturer and it didn't work at all. FYI mine is an E430 with a single blade (not sure if all w210's have the one blade system).