2004 Subaru Impreza Owner's Manual - Page 440

Maintenance and service Washer Fluid Concentration 30% 50% 100% Freezing Temperature 10.4°F (-12°C) -4°F (-20°C) -49°F (-45°C) Replacement of windshield wiper blades Grease, wax, insects, or other material on the windshield or the wiper blade results in jerky wiper operation and streaking on the glass. If you cannot remove the streaks after operating the windshield washer or if the wiper operation is jerky, clean the outer surface of the windshield (or rear window) and the wiper blades using a sponge or soft cloth with a neutral detergent or mild-abrasive cleaner. After cleaning, rinse the windshield and wiper blades with clean water. The windshield is clean if beads do not form when you rinse the windshield with water. Never use engine coolant as washer fluid because it could cause paint damage. Do not clean the wiper blades with gasoline or a solvent, such as paint thinner or benzene. This will cause deterioration of the wiper blades. If you cannot eliminate the streaking even after following this method, replace the wiper blades using the following procedures: 1. Raise the wiper arm off the windshield. - CONTINUED - 11-55