<IMG style="WIDTH: 18px; HEIGHT: 18px" height=25 src=smileys/smiley17.gif width=25 border="0">my benz coolant temperature always rises to app.82 degree celsius during the day but when accelerate it decreases to below 80 degree celsius.At night always stays constant at 80 degree celsius.Its that ok?or maybe the hot atmosphere make the coolant temperature increase.

That's actually a little on the cool side, 87'C is when the thermostat starts to open. Your temps are fine though, just make sure it doesn't go much below 80'C when cruising because your gas mileage will start to deteriorate and engine wear starts to increase.