My 94 maxima temperature guage goes down when I drive the car in cold weather. It goes back to normal when the car is standing. With guage the heat also goes up and down. Now in summer the guage is in normal range but it went down when it got a little cold. I have flushed the radiator but the problem seems to be something else. Any advice?

 

sometimes it could be that theres an air pocket in the coolant system(happened to a friend) ..also try thermostat

 

how do i get rid off air packets? If the thermostat is bad then wouldn't it show high temp reading in summer?