On my wifes Buick, back when it was just a baby {~3 years old}, I siliconed the original serpentine belt periodically to quite the squeal. Then the belt broke and destroyed the underhood mat and I had to stop on the side of the road. Had to pay a ridiculous amount of money at the dealer to replace the mat in addition to buying a new belt.
I don't make it a practice of spraying silicone on the belt anymore. I buy a belt.