FORD 1999 E-450 - Manual (Page 187)

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.
Underbody
Flush the complete underside of vehicle frequently. Keep body drain
holes unplugged. Inspect for road damage.
Inside windows
Use glass cleaner for the inside windows if they become fogged.
Maintenance and care
187