A good way to clean a fiberglass door is to dip a sponge in a mixture of water and mild detergent, and gently work the sponge over the surface. Use acetone or vinegar to get rid of stains and water spots.
Begin by filling a bucket with water and adding a few squirts of mild dish-soap. Dip a clean sponge in the soapy water and gently work the door’s surface. Thoroughly rinse the sponge and clean the surface one more time. Dry the fiberglass door with a dry, clean cloth or towel.
To get rid of oil-based stains on fiberglass doors, prepare the work area by opening all the doors and windows in the surrounding area. Pour a small amount of acetone onto a clean rug and gently scrub the stains, periodically add a small amount of acetone to remove more stubborn stains. Once the stains have disappeared, dip a new rug in plain water and rinse off the acetone. Use a dry rug to dry off the area after rinsing. Substitute vinegar with acetone to remove water spots or other mild stains.
Install rubber or metal door guards at the top and bottom of the doors to protect them from cuffs, scratches, dings and general wear. Door guards also add insulation to the home and may result in saving money on utilities in the long-term.