What might cause squealing in my ten-year-old car?
Does the squealing primarily occur when the A/C is on?
If so, the squealing is very likely from the belt being too loose.
First test for tension by pulling on the belt to judge if it is too loose. If too loose, it should be tightened to specification.
If it is tight to specification, the belt may only need a squirt of belt lubricant to provide the proper level of friction between the belt and the pulley.