I like BMW washer fluid (and VW, for that matter) because it works well and has a nice smell.

Having said that, when driving sloppy roads in winter and adding 4 litres of washer fluid every tank of fuel, I use any -40 fluid that the gas station has.

Agree you have a leak.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue