Here is a good article for ya. Z
http://www.hendonpub.com/resources/article_archive/results/details?id=1091 During the test, the coolant temperature ranged from 50 deg F to 200 deg F, i.e., normal operating temperatures. This cold start-maximum output test was done 1,000 times, for 1,000 hours of engine testing, which represents about 60,000 miles of driving.
In addition to the dynamometer and durability testing conducted at Romeo and Dearborn, Ford conducted high-altitude driving tests in Colorado, where more than 1,000 peaks are over 10,000 feet high. Then they ran extreme hot weather tests at the Arizona Proving Grounds and extreme-cold weather tests at Florida's Elgin Air Force Base. Using a wide variety of fuels, the engine testing was performed at temperatures from
minus 40 deg F to 110 deg F, and at altitudes up to 12,000 feet.