A lot of discussion about serpentine belts lately. They were the most oversold item. As they became harder to install ,due to lack of space in many of today’s engine compartments, they have been replaced by various fluid replacements and the ever fearful cabin air filter. Don’t get me wrong many fluids due need to be replaced as do cabin filters but if I was having my car serviced and someone came at me with a bunch of vials filed with various colored fluids I would say no before they spoke a word. I have never seen a serpentine belt that failed due to wear usually it is from a driven accessory failure. They have to be really in tough shape to fail I mean they can have chunks missing and be frayed at the edges and still perform. Usually they will make some noises before failing I think this is why I have seen very few fail due to wear.Replace the belt when it has cracks the entire length or it is frayed and then check the pulley alignment.