I have a 2000 Pontiac Firebird, 3.8, automatic with 170,000 miles. It's reading low oil pressure and sometimes drops down to zero after driving itva few miles. It typically does good after an oil change but then after a few days it does the same thing all over I have replace the oil pressure sending switch, not sure if the oil pump is bad! Any ideas?

SOURCE: Oil Pressure Drops While Driving

your oil pump is either weak or there is sludge i9n the oil pan. my adives is to have the oil pan dropped . chances are sludge is the culprit. as the oil get's warm the pressure should only drop slightly but pressure is generally dictated by engine rpm. pumps are gear driven so if it was a bad pump your oil pressure would start out very low at start up.

SOURCE: 2000 PONTIAC FIREBIRD FUEL PUMP REPLACEMENT

Many of the Pontiacs of that era up to even present models had an access panel in the trunk that you could access through the back seat pass through.

Its been a while since I seen the inside of a Firebird, but in thinking about it the back seat pass through may not be present on the Firebird, but it may be worth the time to lift up the carpeting in the trunk area and see if there is an access panel to the fuel pump.

SOURCE: Oil pressure suddenly dropped to zero.

Hello, let's see what you need.
Yes, the pump can go out that fast.
Do not start your engine. Go out and check the oil. If you have plenty of oil you will need to tow it to a shop. If your out of oil check the the drain plug on the oil pan and check the oil filter.

SOURCE: drop in oil pressure

The oil sending unit could be bad, or the pressure relief valve in the oil pump is malfunctioning.

SOURCE: Pontiac Bonneville(2000) oil pressure sending unit

The oil pressure sending unit is located behind the oil filter, Threaded into an aluminunm housing. It has wiring that plugs into the sending unit. The oil filter has to be removed and you will need a deep well socket and a 6 inch extension. Change the oil and the sending unit together.