Ford 2003 Mustang Owner's Manual page 189

Maintenance and care
Cleaning and maintaining the safety belts
Clean the safety belts with a mild soap solution
recommended for cleaning upholstery or carpets. Do
not bleach or dye the belts, because these actions
may weaken the belt webbing.
Check the safety belt system periodically to make
sure there are no nicks, wear or cuts. If your vehicle
has been involved in an accident, refer to the Safety
belt maintenance section in the Seating and safety
restraints chapter.
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