My 135i has been outside for months. My last application of Z2/Z5 was a long while ago - May. It has had one application of ZCS since. Well I washed the car today as it had some grime and droppings on it. I have to say that because the car had some grime on it, it wasnt beading well. I know, I know, beading isnt always a good indicator of protection... I was surprised when during the wash, it really beaded and shed water very well! And it reflected nicely, even before I applied ZCS. Not bad for being in the sun all summer!