Pontiac: HATING PROBLEM, oil pressure gauge, oil pressure sending unit

Question
I HAVE A 1987 GARAN DAN IN WHICH I HAVE A PROBLEM WHEN I AM AT A STOP SIGN MY CAR STARS TO HEAT UP BUT WHEN I AM DRIVING EVERY THING IS OK.
I CHANGE THE THERMOSTATUS BUT NOTHING HAPPENS IT IS STILL THE SAME.MY SECOND QUESTION IS THAT MY OIL PRESSURE GAUGE SHOWS THAT THE OIL IS LOW BUT I CHECK IT AND EVERY THING IS OK. PLEASE GIVE ME YOUR ADVISE.
                   THANK YOU.


Answer
How long a stop are you talking about, if it's a LONG stop and it heats up but does not overheat then that's normal, otherwise it is probably and air bubble in the system.  In my Fiero since getting the air all the air out takes some real precision coolant filling I found out that if there is air in the system it would seem to heat up more, and heat up FASTER than if the system had no air in it.  I know what you mean,  all of a sudden it will go up pretty quick, but not suddenly and then when you begin to move it goes away.  The reason is that when you accelrate the engine even when stopped you churn up the bubble and it gives the sensor in the cylinder heaads the proper reading, you might make sure you get out all the air.  try tilting the car backwards, with the back of the car lower than the front that way it will help make any air go to the radiator, it might work.  Other than that I could not think of anything else.

As for the oil press. problem, you probably have a bad oil pressure sending unit.  In most cases it is somewhere near the oil filter, but it is usually obvious where it is if you look around and follow any tubes that might be leading to the oil filter area.  Changing it should solve your problem unless you guage is bad, which is possible, or that you have faulty wiring somewhere.