Your windshield wipers perform a vital role in allowing you to drive your Mini Cooper S in bad weather. Unfortunately, your wiper blades will eventually start to wear out from use, age and weathering. When this happens you will need to replace the wiper blades, but this isn't difficult. Just make sure that you buy windshield wiper blades that are designed for a Mini Cooper S of your model year, with an airfoil wing attached if possible.
Pull the windshield wiper arms away from the windshield. This will keep you from accidentally scratching your windshield when removing the old windshield wiper blade.
Use your flathead screwdriver to remove the clip that holds the windshield wiper blade in place, making sure not to use too much pressure or you may damage it. Remove the windshield wiper blade and set it aside.
Use the windshield wiper lubricant to clean and prepare the new blades; this lubricant should come with the blades, most likely on a moist towelette. Make sure that the rubber of the blades is completely covered when you wipe it on.
Clip the new blades onto the windshield wiper arms; if you are using blades that have airfoils on them then make sure that they are facing in the right direction (the airfoil wings on the wiper blades are used by the Mini Cooper S to help to hold them to the windshield.)
Return the wiper arms to their previous position, making sure that the rubber of the blade lies flat against the windshield.
Check your windshield wiper blades for wear and damage every three to four months to keep your foul-weather driving as safe as possible.