Wiper blades should be change don a regular basis, relative to how much of a beating they take. In general advice you should probably be looking to replace them once or twice a year, but a particularly bad winter or a violent storm might make you consider doing it more frequently. It goes without saying that somebody in the Scottish highlands might want to replace them more than somebody in Cornwall.
Winter is when you really need to be looking at your wipers, they will be used a lot more to combat the rain and snow. The weight of snow, hail and heavy rain will also put them under more pressure and you may find the motors wearing out, springs stretching or rubbers splitting as they work over time.
Replacing wiper blades is a straightforward, if not irritating, task. Different manufacturers will have their own technique, fixture or fitting but they all share some common ground. When you're considering replacing your wipers, make sure that you go to an auto centre and ensure that you get the right product for your car. Bear in mind that rear wipers will be different and the two wipers on the front windshield may be different lengths. Try to undertake this job on a clear, sunny day.
Firstly, you want to pull the windscreen wiper towards you. You'll feel some resistance as the spring stretches but it will hold in place when fully extended. The wiper itself will have a small tab or notch on it which is pushed in to release a catch. Finding this might be difficult but the vast majority of manufacturers have these, so keep looking. Push the tab in and the wiper should release, you may have to fiddle to get it off but don't be afraid of it breaking. We're not saying don't be cautious, but these wipers can withstand a pounding of snow and rain normally.
Be careful of the fiddling, you don't want to suddenly pull the wiper off and end up scratching or cracking the windscreen. The same goes for the arm of the wiper; once you have the wiper off you will be left with a metal pole extended from the windscreen on a tension spring. Don't let this flick back into place as it could crack or shatter the glass.
Grab your new wiper and slot it onto the catch which was released by pushing the tab. Once you have it threaded on, you want to slide the wiper across so that it is fully in contact with the metal arm. Judge it on how your wipers looked before, you should be able to tell if it's on properly. It will click into place when you hit the sweet spot, give it a bit of a pull and tug after you hear this to ensure that it's fully caught. When you've replaced it, give it a quick blast when you're in a safe location. You don't want to drive off and end up using it for the first time during a rainstorm, be sure that it works before you leave home or work.