Temp fluctuating

So if I'm reading this right.

You are concerned that the engine temp with a 180 deg thermostat is running at 185 to 187 and when you slow down the temp goes down?????


That seems 110% normal.

When I'm running at 75 my temp is a little higher than when I'm running at 60.

I have more wind resistance and need to create more HP to push the car through the air.

Slow down and less needed HP thus less heat.

At idle ( assuming a good shroud and proper fan etc and I am producing very little HP thus lower temps.

(Side note... If the cooling system at idle is not properly efficient the temp will rise)

BTW electronic gauges tend to react instantaneously, vs thermoelectric.

If you have ever had an electric gas gauge you may have noticed it swinging wildly as the fuel sloshes around.