Wipers are a safety item that almost everyone ignores until it is raining hard and they cannot see. In Australia they wear out faster than most people expect, because it is sunlight, not rain, that kills them.
How long do they last?
Plan on replacing them every six to twelve months. UV and heat make the rubber harden, crack and lose the sharp edge that wipes cleanly. A car parked outside in the sun will go through wipers much faster than one in a garage.
Signs it is time
Streaks left behind after each pass. Sections the blade misses entirely. Chattering or juddering across the glass. A smeary film instead of a clean sweep. Visible cracks, splits or a wavy edge on the rubber. Any of these and they are done.
Try cleaning first
Sometimes the problem is grime rather than wear. Lift the blade away from the glass and wipe the rubber edge with a damp cloth — you will often be surprised how much black residue comes off. Clean the windscreen properly too. If the streaking stops, you just saved yourself the cost of new blades.
Replacing them
Most blades clip on and off in a couple of minutes with no tools. Take the old one with you or check the size online for your exact model — the driver's side and passenger's side are often different lengths. Replace them in pairs so both sides perform the same.
Lay a towel on the windscreen while you work. If a bare metal arm springs back onto the glass, it can crack it.
Small habits that help
Never run wipers on a dry windscreen — it tears the rubber and can scratch the glass. Use washer fluid first. Clear leaves and grit from the base of the windscreen. If you park in full sun, lifting the wiper arms off the glass keeps the rubber from baking onto hot glass. And scrape frost off rather than using the wipers to clear it.
Do not forget the rear
Hatchbacks, wagons and SUVs have a rear blade that gets forgotten for years. It wears out the same way, and it matters most when you are reversing in the rain.