Question

You should check your windshield wiper fluid level ___________.
Every day
Every week
Never
Every six months

Answer 1

i would say every 6th months. it could be a week but that sounds 
too often

Answer 2

You should check your windshield wiper fluid level "every six months".

Windshield washer liquid (likewise called windshield wiper liquid, wiper fluid, screen wash) is a liquid for engine vehicles that is utilized in cleaning the windshield with the windshield wiper while the vehicle is being driven.  

Windshield washing liquid is a vital piece of keeping up your vehicle. Most commercial windshield cleaners contain methanol, a toxic substance unsafe even in little sums.