I needed a cooler for a double Master test In Lost Hills, California. I would be tent camping for four days but mid-May usually doesn't get too hot. I didn't expect the temperature to get over 90. Based on this thread (and some additional research) I decided to try the Coleman Ultra Xtreme 58 quart 6 day cooler. Coleman rates this cooler "6 days at 90 degrees".
Wednesday mid-day I packed the cooler with 2 one gallon plastic water jugs frozen solid. I then placed enough food and drinks for four days. Over this I added 20 pounds of ice cubes. There was still room for an additional 4 pound block that I placed on top. This totaled 40 pounds of ice or about 20 quarts or just about one third the capacity of the cooler.
It was still daylight and pretty warm Wednesday evening when I finished setting up. The surprise came Thursday when the temperature hit 108! Friday was also very hot. My vehicle thermometer read 107 at one point. It wasn't till Sunday that the temp dropped to around 90. The cooler had been kept in the closed tent which was stifling during the day.
When I got home Sunday PM the two ice jugs were still half frozen, the 4 pound block was 75% melted and there were still some cubes floating in the water. What food and drinks that were left over were still cold.
This cooler was not designed for bear country but for the dog games where it will be in the back of a truck or camper I don't think you can beat the value.