I've had an intermittently squeaky belt for the last ~10k miles that I believe to be from some oil reside contamination following an engine cleaning after I found oil leaking out of my throttle body connection (I also cleaned my CAC, intake and installed an OCC at the time).
I purchased a replacement belt, but decided to try some SilGlyde as a quick fix for poops and giggles. A dime size dab on each side of the belt, and it was dead silent... for 3 days.
After a week, the squeak/squeal is substantially worse now, and it never really goes away (as it did before after warming up).
New belt goes on this weekend sans SilGlyde.

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