Wiper blades not only keep rain water off a car's windshield, they also help provide a clear viewing area for the driver. Therefore, keeping your wiper blades working and in top shape is important. Hardening of the blade's rubber, however, can reduce their effectiveness. This hardening occurs naturally over time as the blades are exposed to sun and other elements. If the rubber on your wiper blades has hardened, a few things will help restore their usefulness.How to Soften Wiper Blade Rubber (Gabriel Garcia/Demand Media)
Lift the wiper blade arm up and away from the windshield. This will give you easy access to the blades.
Inspect the blades for cracked or torn rubber. If the rubber part of either blade is torn or frayed, then the blade needs replacing.
Put a small amount of vinegar on a cloth and gently wipe the vinegar the entire length of both of the rubber wiper blades. Wipe the blades twice, gently, making certain that the vinegar has cleaned the blades as well as soaked into them.
Wet another cloth with plain water and gently wipe it along the rubber of the blades to remove any excess vinegar. Wipe with a dry cloth to dry the rubber.
Dip a cloth into petroleum jelly and wipe it along the entire length of the rubber of each blade, making certain that the jelly has a chance to soak into the rubber. Do not wipe off the blades; allow the petroleum jelly to air dry for at least 10 minutes.
Lower the wiper arms back onto the windshield. The rubber on your wiper blades has now been treated and should work for several rains.