I've been noticing that my oil pressure gauge is getting close to 0. When the engine is on,the needle is positioned at about 1/3. When I press the brake, the needle moves to the left. What is going on?

There could be a number of things happening.

Do you change the oil yourself, if so..have you noticed any silver/gray pigmentation to the oil?
This would possibly mean the oil pressure gauge is right and your main bearings are going bad. There might also be a deep knocking sound from the lower motor once you are up to temp.... any of that?

I would recommend having it tested with a mechanical gauge for accuracy. If the gauge or sender is bad...it is possible that you are getting the low reading. However...it is typically our experience that a bad sender indicates a high or pegged high reading.

How many miles on the car?

Our oil pressure gauges are known to be flaky. Take it to a mechanic and have him confirm a genuine pressure reading with a mechanical gauge.

PogiGreg,

Check your PM

Andrew

This is a new engine i just had put in. The engine runs great. no problem. I just checked with my mechanic and he put on a new oil pressure switch. He said everything was fine. It has plenty of oil. Could we be dealing with a flaky electronic gauge on the cluster?

Did he check the oil pressure with a mechanical gauge? If so what was the reading? If not, go have it checked by him. Like I said, the gauges are inaccurate and every mechanic I talked to says that GM oil pressure gauges are ****. They're mere guidelines more than anything,

Its reasonable to assume that the contacts for the oil pressure gauge are dirty or corroded. With the way AllData describes how it works, the lower the oil pressure, the greater the resistance, thus resisting current flow to the gauge. If you got something on the contacts thats resisting current flow, you will get a lower than normal oil pressure reading.

You will never know for sure until you get a mechanical gauge hooked up.