Picked this stuff up at NAPA. I was using wheel bearing grease in my window channels, but apparently using that with Rubber leads to it caking and becoming very un-lubricating. I was using the spray silicone, but it would gunk up after a couple weeks, need to be re-applied and my windows would keep tilting.
I modified my regulator/up-down bracket so that the windows don't tilt anymore, and I removed, cleaned and sil-glyded the rubber channels. The windows are finally working fine.
I'll let people know in a few weeks if this stuff is as good as I've heard. It supposedly won't gunk up and is water repellent.