Engine overheating

I have read that the probe isn`t long enough on thse to be accurate, especially on rads. that like to run a little low .-???????????
The antifreeze needs to be 'topped off' so it can touch the probe. As to accuracy, I also installed a 'pro' temp gauge that the probe screwed right into the radiator, which I assume is the location for an electric fan probe. Both gauges were within about 5deg of each other.

Radiator dual guages small.jpg

Radiator dual guages small.jpg
Elect fan probe location circled