Can you premix coolant with distilled water and store it for future use? I have about one-fifth of a gallon left and would like to premix it so that I don't have to store it and a separate bottle of distilled water. I read somewhere not to do that but can't think of why it would be bad or wrong to do so. In case it matters, the coolant I have is Prestone orange 5/150 extended life.