Do the temperature and oil pressure gauge directly display the actual measured conditions. Although this is my first diesel, the gauge indications act strange. The temperature reading goes to the center mark and then 3/16" below the center mark then repeats. The movement from high point to the low point takes only 15 seconds. It doesn't seem like the actual temperature could change so quickly with the large amount of coolant and iron in the engine. And sometimes the temperature will drop more than 3/16" when idling and sometimes the temperature will go above 1/8" the center mark when idling. Going above concerns me because it has occurred when air temperature was in the low 70s.

The oil pressure also seems to change with the quick changes in the coolant temperature. The oil pressure should be influenced by the oil viscosity, which is related to the oil temperature. But I don't see how the 12 quarts oil could change temperature fast enough to have the displayed effect on the oil pressure. In addition, it takes approximately 1.5 seconds for the oil pressure indication to move above zero when starting, even if the engine is restarted immediately.

Is this normal or should I have it checked?

 

It has been said that the gauges DC gives you are just digital indications of what the computer says you want to see.
If you want real gauges then you will have to install them yourself

 

The temp is probably real. But it is driven by the computer. So it's not going to be 100% smooth, there will be steps. What you might be seeing is the temp switching from say "120" to "121" in the computer's mind. And when near a line you notice the step more.

Many vehicles I can even see the speedo and tach move in chunks like this.

 

Steve is right. Coolant temp is real, oil pressure is a switch. Same goes with the fuel level but in the opposite sense. If you leave your truck running when you re-fuel, you will notice that it takes forever to get the needle to the Full position (long after you have left the fueling station), but if you cycle the key, the gauge goes instantly to the F mark. Its because the ECM is averaging the reading to make the movements smooth.