Known issues regarding windshield wiping are, motion resulting in streaking or sheeting, formation of water drops after wiping and bouncing or blade chatter. Streaking is normally brought by wiper blades with road film or vehicle wash wax; this can be corrected by washing the blades with soapy water; failure to which means replacement. They should be replaced as often as for twice a year - before and after the season when the roads are heavily salted. If the spring tension is weak, the tension spring which pushes the wiper against the glass should be checked and if weak, the wiper arm should be replaced. Errant water drops on the windshield after wiping after are as a result of oil, road film or diesel exhaust which can be cleaned using alcohol or ammonia solution or a non abrasive cleaner. Blade chatter may be caused by dirty or worn blades, a dirty windshield, bent or twisted wiper arms; cleaning the blades and windshield, putting the wiper arm through a test in order to get the blade to apply even pressure across the windshield and also making sure that the blade is perpendicular to the windshield when not in operation. It is also recommended for example to occasionally apply light oil to the wiper linkage which can be found on the driver's side of the car bonnet. Should problems continue, the blades may be excessively old or deteriorated and should be changed.