I had 4 cases of Diet Caffeine Free Dr. Pepper in my basement for almost 2 years. Year round it was about 60 degrees down ther with no direct sunlight reaching the cans. Before I threw it out I had to taste it. It actually tasted normal.
I took into account that no direct sunlight and a constant low temperature preserved it.
At the same rate, I have had a 2 liter Pepesi that was in date and that had been stored in a gravity feed shelf up against a window at a convenience store....The sunlight just about bleached out the label and the constant change in temperature broke down the sugar and preservatives. Nasty
Back to your original ?? If it is original Crystal Pepsi I would'nt buy it to drink, however, if you are a collector and it is in good shape and the color of the product and the label is in good condition I would buy it.
Whether you think can or think you can\'t, you\'re probably right!