I would use a mixture of about a cup of distilled water to a couple tablespoons of white distilled vinegar. You can use regular water, but I like to use distilled to keep any mineral deposits (ie streaks) off the window.

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Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record