What is the recommended miliage/months for a transmission fluid change/flush for a 2009 Escape Hybrid. There is nothing in the manual under the scheduled maintenance section (which I thought was strange). I saw something online that implied you should change at 30,000 miles which seemed quite low to me. My 2004 Chevy Malibu is scheduled at 150,000 miles (currently has 130,000 miles on it and runs perfectly). If it is 30,000, why does it need to be changed so often. Any help would be appreciated.