Belt conditioners are just another version of oil. They mask the noise, but don't help overall. To have a belt work without complaint, it must have clean and dry pulley surfaces, and the belt itself must also be clean and dry. Dry being without any sort of lube or conditioner. The other thing required is tension. If your tensioner is spring operated, it might just be getting tired.
If you source your belts from Belts-R-Us instead of some brand you have heard of, it may be they used an inferior compound in manufacturing, and it will never work without whining and squeaking its complaint. In short, go with a name brand belt that has not been on the shelf at your sunoco for the last 12 years. The rubber part dries out over time and loses its grip and flexibility.
If you have a belt that chirps only at idle, it is likely the power pulses of the engine that are accelerating the crankshaft, causing very slight but noisy slippage. Turn up the radio or the idle. A belt needs some 'wrap' area, the contact area on the drive or driven pulleys. IF the belt does not have enough contact area, it will not be able to transfer power without complaint. Look at your setup to see if the designer gave the belt enough 'wrap'. If not, I don't know a solution other than different pulleys or doubling belts...
One belt to look at is the one that has the 'interrupted' splines. That will allow the belt to reverse wrap without causing premature wear, and may offer better grip as the splines will pretty much stay the same. A belt with cracked splines is not necessarily in need of replacement. You may/can find a FoMoCo blurb to that effect, though if you have State Mandated Inspections, the inspector will likely fail your belt no matter what you show him/her. They 'know' better than the manufacturer, doncha know?
tom
Welcome Visitor! Please take a few seconds and 
