Gauge scale-What are they saying?

My temperature gauge goes to about 7/8 of the scale when the 180 degree thermostat opens and brings it down to just over half. At hot idle I`ve got about 50 lbs. of oil pressure (measured mechanically)and the factory gauge reads just under half way.I have to agree with Jim, these gauges are vague,unreliable,are probably never the same in any two cars, and are only there in case the !@#$%^ really hits the fan. Now that I`ve measured the engines normal conditions with other mechanical gauges ,I have a good idea as to where they should be and will only use them as a benchmark.