[ZeGermanHam]

Originally Posted by AG

When the car is fully warm take the cap off the radiator and put an accurate digital thermometer in to check the temp.

This seems like the most sensible approach.

Also, OP it appears you are not using the infrared thermometer in the most accurate way possible in some instances. Although the laser dot shows you generally where you are pointing it at, the actual infrared light that measures temperature is emitted from the device in a cone shape. The farther away you are from the object being measured, the larger the cone will be and you will get less accurate readings as a result. I usually try to get within 3-4 inches of whatever I'm measuring. In the instance where you measured the t-stat housing, I'd get much closer and measure the actual metal housing and not the rubber hose.