I often will buy the 5 quart bottles because they were are better deal, but my car only takes 3.9 quarts at a time, and my wifes trucks takes 6. Either way I am left with some in the bottle at the end. My question is, if I put the non air tight cap back on it and store it in my shed will it still be good to use later down the road? OR will it have lost some protection properties.