Squealing belts in your X5 can commonly be caused by moisture in the engine bay or an unconditioned and worn belt. While there is not much one can do about the former, the latter can usually be resolved with the simple application of belt conditioner. Belt conditioner, also known as belt dressing, can help restore the surface of worn rubber belts and reduce any squealing noise. It comes in both aerosol cans and tube form.
Pop your X5's hood and go to the front of the engine bay where the belts are located.
Apply the belt dressing to your hands and thoroughly rub it into both sides of the belt if using a tube. If using a can, spray the dressing on the belt, holding the can approximately 1 inch away from the belt.
Turn on your car's engine to allow the belts to rotate for a few minutes.
Lightly apply more belt dressing to the belts and close your hood to complete the procedure. Start your car again to ensure that the squealing has subsided.
