i have two cars running nice autometer gauges. for those unfamiliar, these are top shelf gauges. both cars seem to run about 10-15 degrees higher than the thermostat setting all the time, even when it's cool out. one has a new aluminum radiator and still does it. my question is; both cars have a sending unit placed right beside the thermostat, is this the most accurate reflection of engine temperature? i am thinking not since it would be the very hottest coolant in the entire engine. right? but still, wouldn't you think it would be closer to the thermostat setting since it's within a couple inches of it? anyone else have this problem? i know GM placed the sender in the drivers side head. that would read differently right? any experts on this subject?

What happens when the thermostat closes? one side will be hotter than the other until it opens.