I bought 5 quarts of Mobil1 "Advanced full synthetic Motor Oil" at Walmart. (5 quart container). I didn't use it for about 2 years and kept it in my garage cabinet together with other oil containers. After about 2 years I saw a large oil puddle at the bottom of the cabinet: It was the Mobil1 container which had developed a crack at one of the corners. I also noticed that the plastic had changed its color from silver to yellow. Obviously the material used for the packaging is not resistant to synthetic oil.
I called Exxon Mobil and they asked me to send them pictures. After they received the pictures they asked me for a receipt (of course I don't keep each single Walmart receipt for over 2 years...) No apology, no offer to replace the bad container.
These containers should carry a warning on the label saying that the oil has to be used within a few months. Exxon Mobil does not care about the quality of the products or its customers. I will never ever buy Mobil motor oil again !