Just one quick note seeing I just added some to both of my cars and thought it would be good to comment on it.  For the yankees out there, make sure that the fluid in your windshield wiper fluid reservoir is good for at least -20°F.  Sometimes you can buy fluid in the summer that can and will freeze so it's a good idea to use it all up and put in the winter blend before it gets really cold outside.

 

Additionally, buying that de-icer stuff is a great idea; it works amazingly.  It usually costs more but when you spray it on your frozen windows the ice just melts off.  It's awesome!  Here is a link to Auto Zone which will provide some details about de-icer washer fluid.