I drive a 1995 1.3(petrol) Honda civic HB. The temp always stays 1/4 up the gauge on normal city driving, however when on the expressway or motorway, the temp goes up to 3/4s of the gauge or even higher esp when my speed hovers between 60-70 mph. and it goes down if i reduce my speed. is this normal? or does my thermostat needs replacing?