for a quick fix and cheaper than belt dressing, try a tiny bit of WD40. dont soak it but mist it. it will stop the squeal and you still won't lose any grip on the pulleys as long as you use it sparringly and while the engine is running. just remember belts are cheaper than just about any other engine part, always check for wear and seating when you change the oil and adjust as needed.

 

wd-40 will eat the belts and make them more slipery!!!!!!!!!!!!!!!!!!!!