Temp gage fluctuation

I have a 2003 LA1 impala (3.4L). I have noticed that all the current Chevys we have and the past ones for the most part after a few minutes driving the temp gage goes to a setting and stays steadiy. My temp gage sort of tracks the weather, when cold it stays on 160 - 170. While durring the summer it usually is around 200 -220 unless freeway driving where it will drop 20 degrees. I have seen other impala's where the temp gage stays at the middle ( 200) no matter what the wheater...our 2006 Malibu also stays at 200 , center of thr gage.

I have a 2003 LA1 impala (3.4L). I have noticed that all the current Chevys we have and the past ones for the most part after a few minutes driving the temp gage goes to a setting and stays steadiy. My temp gage sort of tracks the weather, when cold it stays on 160 - 170. While durring the summer it usually is around 200 -220 unless freeway driving where it will drop 20 degrees. I have seen other impala's where the temp gage stays at the middle ( 200) no matter what the wheater...our 2006 Malibu also stays at 200 , center of thr gage.




the thermostats are a problem ...after market T stats are not equal and it I have found requires a high quality part...the low quality part will not correctly regulate the temp..

the other componet is the correct coolant and mixture with distilled water..and coolant system condition.

The thermostat is the factory one as far as I know.
I drained the coolant from the rad and block. Filled with I think 50/50 dexcool and distilled water. The strange part was I could not put in the full amount it said should go in ( helm factory manual). I even removed the threaded plug next to the knock sensor to drain the block. When filling I opened the small screw vents on the top rad hose block fiting.

The thermostat is the factory one as far as I know.
I drained the coolant from the rad and block. Filled with I think 50/50 dexcool and distilled water. The strange part was I could not put in the full amount it said should go in ( helm factory manual). I even removed the threaded plug next to the knock sensor to drain the block. When filling I opened the small screw vents on the top rad hose block fiting.

this amount should be 3.5 gallons...the heater core /hoses trap 1-2 quarts...

I carefully capture all drained coolant and then use that drained amount to calculate the correct mix...

since you did this properly I suspect that the coolant temp will be better...

..thats probably where the coolant was..in the heater core.. I did the same, I used one of those big galanized pans made for such procedures , then poured into a 1 gallon jug, what I got out was also less.

No unfortuately it did not, temp gage still the same.

..thats probably where the coolant was..in the heater core.. I did the same, I used one of those big galanized pans made for such procedures , then poured into a 1 gallon jug, what I got out was also less.

No unfortuately it did not, temp gage still the same.

I didn't see that you replaced the thermostat....If not replace with a high quality one as this will keep the engine temp correct if the coolant is good and clean...since you have no operating engine issues this is all I would expect is the problem...these thermostats are good for 4-5years and I usually replace when the dexcool is serviced at the 3-4 year point...on my vehicles..