I have a 2007 Grand Prix base engine, and have noticed that the transmission temperature has gone up over 220 degrees during normal mixed local driving on a 90 degree day yesterday here in NY. According to the owners manual normal operating temp should be between 190 and 200. 223 seemed a little high. The fluid level is at max. Recently have done the trans service, cooling system flush incl heater core which was clogged, replaced thermostat, new trans lines to and from radiator, and just replaced the coolant bypass elbows, and bled the system. Engine temp gauge goes over half way after driving around for 30 min before going down below half way. Any advice? How high is too high for the transmission temp?