the squealing noise on belts is the belts grabbing then slipping over and over again. It is a misconception that you want the belt to be "sticky" to grab the pulleys better. This actually makes the issue worse. As the belt wraps around the pulley it will always stretch and move on the contact surfaces. The "stickier" they are the worse the squeak. Think of wet sneakers on a tile floor. At the dealership we would hit the belt with brake clean, hit it both sides with a wire brush and then put a small dab of the silicone high temp brake grease on both sides. Just a small dab on the tip of your finger the size of a peanut M&M or smaller. The belt will not slip due to the tension but it will slide into and out of the pulley groves with no squeal. And it is a lasting fix. Side note though, make sure your pulleys are all lined up right. If one is out of line it will squeal all the time. Worse with serp belts.