Do not use belt dressing or conditioner on the serpentine belt; it is intended for V-belts. If the belt is coming off, inspect the tensioner and idler pulley, confirm the belt is seated in the correct grooves, and replace a worn belt (Gates belts with ribs on the flat side were recommended). With high mileage, also check components driven by the belt.
The owner of a 2001 Dodge Grand Caravan with 90,000 miles asked whether belt dressing and conditioner are bad for serpentine belts. The expert said not to use dressing because it is meant for V-belts. If the belt comes off, check the tensioner or idler pulley, make sure the belt is not one groove off, and consider a quality replacement belt. Related driven components may also be involved at that mileage.
