does any body know what might be happening to my girl friends 1992 300d 2.5 turbo. this car is equipped with washer fluid resovior that is heated, after only 2 or 3 weeks the the blue washer fluid turns some what greenish and does not clean the windshield very well and also leaves a sort of smeary haze. is the heat chemicaly changing the fluid, and if so is there a recomended washer fluid for a car with a washer fluid heater, thanks.