Thermostat the problem????
 

1992 1.5L Civic's engine temp takes awhile to get to normal operating temp according to the guage. It's more obvious now because of the cold weather. When the heat is turned on the gauge will go down. Turn off the heat and guage will go back up. I guessing it's the thermostat. Advice welcome.

during cold weather it takes more time to warm up your car, if you turn on the heat during warm up you are takeing heat/power from the car...henst why it takes longer for your guage to raise. i doint think there is anything wrong...mine does the samething. once you warm the car turn on the heat, if you go on the highway open the vents for out side air and turn off the heat..the heat will get pushed inside your car from the engian keeping your car nice and warm...saves on gas from what i have seen....some info and some advice from my experances

The thing is once the temp gauge gets to the normal operating temperature according to the guage once I turn the heat on the guage starts to go down.

It sounds like your car is fine.... the reason the guage goes down one the heat is on is because you're releasing the heat into the car.... that's why you turn on the heating if you see your car starting to overheat.....