temp guage

What is your question?

how do u kno wen the thermostate is the problem. because i done change mine a couple of time. my car tend to run hot one day then the next day driver perfectly find. and once in a while if its been sittin for a long time and i drive it. once the temp meter start movin it will go str8 to the red them come all the way back down to the cool position after i been drivin for a while. then want do it again. why is that