Based on my experience, and several others, the analog gage is not an accurate measurement of engine temperature. For example......

I have, on several occassions (Sunset Point), reached 235+ on the DIC indicator....... I drive with the DIC in "temp" mode MOSTLY all the time. The analog moved MAYBE less than a sixteenth of an inch. Now I suppose you can diagnose from this, but it would be tough. Several others have noticed the same thing.

That makes me wonder which system is actually closer to the temp??? I mean prior to dic displays all we had was the needle and it (without air pocket and/or bad sensor) was considered a reliable indicator of your coolant temps. Have you or anyone taken any temp reading with say a laser thermometer on the hoses or radiator? Or is it that the needles sensor is just slower to react to changes?

Temperature sensors in automotive applications are overwhelmingly of the "thermistor" type. That is - at different temperatures, the sensor exhibits a different electrical resistance, and the amount of current flowing in the electrical circuit changes. The amount of current flowing in the circuit is correlated to a displayed temperature.
High-quality thermistors are typically made from platinum or another precious metal alloyed with a suitable lower-cost metallic conductor. Their characteristic resistance gradients are known, stable, and are a foregone conclusion and have been for decades. If the electrical contacts to the thermistor are intact and the circuit is complete, the temperature reading cannot be wrong. The DIC coolant temperature reading is unerringly correct if the circuit is working.

The analog gauge in the HHR typically moves to the small hash mark just below the half-way mark on the gauge, and stays there. The HHR's acceptable operating temperature range barely moves the needle. It's function is to assure the operator that everything is in order - not to illustrate every minor variation in coolant temperature.

The OEM thermostats in Ecotec engines have a tendency to stick in the open position. This causes a wide variation in temperature readings when idling as compared to moving. When coolant temperature becomes a concern, go straight for the thermostat and eliminate it as the source of possible trouble.

jennybeeb,

I have over 160,000 miles on my panel with the 2.4L and have used it in all situations including over 30,000 miles of towing a trailer that weighs right at 1,000 lbs. The cruise temp is always at 180 to 192 and climbing a 5 mile 7% mountain grade with trailer at 55 mph only got it to 204 degrees . Idling will make it go up just a notch to 195 degrees. I have had it serviced by dale earnhardt chevrolet and use mobil 1 oil.

This is one of the main reasons i want the trifecta tune. have them set the fan turn on point at 180. I dont know about you guys but my 2.4 manuals performance takes a **** when temps start going up like 190 or so when at a light or going up an incline its really annoying. That along with PED makes this car suck sometimes.

coolant temp fluctuations
 

I have 103000 on my '08 SS and noticed that my temp gauge was going up to 220 degrees at times. I added coolant to the overflow tank and it settled down to a steady 190 to 195.

Settings the fan to a 180 turn on would mean the fan would run all the time.

Ya I know but when the temps are down I get better economy and power. You guys have any cooling mods that can help keep the temps down without having the fan on all the time?

x2.

Leave it be - the engine, like most now a days, is designed to run at the designated temperature. If you mess with it you will have drivability and emmisions problems.