GMC 2013 Savana Owner's Manual page 336

For vehicles with high gloss
surfaces or vehicle displays, use a
microfiber cloth to wipe surfaces.
Before wiping the surface with the
microfiber cloth, use a soft bristle
brush to remove dirt that could
scratch the surface. Then use the
microfiber cloth by gently rubbing to
clean. Never use window cleaners
or solvents. Periodically hand wash
the microfiber cloth separately,
using mild soap. Do not use bleach
or fabric softener. Rinse thoroughly
and air dry before next use.
Use a soft microfiber cloth
dampened with water to remove
dust and loose dirt. For a more
thorough cleaning, use a soft
microfiber cloth dampened with a
mild soap solution.
Do not use cleaners that increase
gloss, especially on the instrument
panel. Reflected glare can decrease
visibility through the windshield
under certain conditions.