Window channels
 

Hey. Several years ago I was with a friend when he was getting his electric window repaired (the window was off track). The man who worked there said that many problems are caused by the window getting 'sticky' in the channel and when you press the button to roll it down it puts stress on the system (currently, my windows always sound like they 'break loose' when I first roll them down). He recommended a spray to use regularly in the window channel to keep the window working smoothly. Now, for the life of me I cannot remember what that product was. All I do know is that is definitely wasn't WD40. I've thought silicone, but I don't remember him saying that and when I have tried that it hasn't really made a difference. It sure seems like whatever he said had a number or letter though.
Just wondered if anyone out there might know what this is, or if you've used anything yourself.
Thanks.