People have a thinking that the thermostat is 195 degrees. You notice in the GM service manual they state the opening and full open temp values

Completely submerge the thermostat in heated water. The water should be 11°C (22°F) above the temperature indicated on the thermostat valve.
Thoroughly agitate the water. Under these conditions, the thermostat valve should open.
Replace the thermostat if it does not open at this temperature.
In order to inspect if the thermostat valve is closing properly, perform the following test:

The thermostat should begin to open at 87°C (187°F) and fully open at 100°C (212°F).

Completely submerge the thermostat in heated water. The solution should be 6°C (10°F) below the temperature indicated on the thermostat valve.
Thoroughly agitate the water. Under these conditions, the thermostat valve should close completely. The thermostat should be fully closed at 80°C (176°F).
Replace the thermostat if it does not close at this temperature.