1996 Chevy Impala Engine Oil Light

During city driving the engine oil light will come on after coming to a stop at a signal or stop sign. I know that there is enough engine oil in the pan because this occurs even after just changing the oil and filter. This occurs mainly after the engine has had time to warm up. I have a side entry garage at home and I have to turn the steering wheel to the stops sometimes to maneuver the car into the garage and the engine oil light comes on while I do this too. Is there something wrong with the oil pump maybe? This is the second engine in the car, changed at 110,000 miles with a used engine with 30k already on it, so I've got approx. 240k on the current engine...