For 1990-2009 cars

1. Remove the wiper blades from the wiper arms. Refer to Windshield Wiper Blade Replacement .
2. Look down the length of the blade element.
3. Replace the wiper blade element if the rubber element which contacts the glass is deflected more than 15 degrees from the centerline of the blade. Refer to Wiper Blade Element Replacement .
4. Install the wiper blades on the wiper arms. Refer to Windshield Wiper Blade Replacement .