The valve train noise can be a result of many different things. It can either be from dirty hydraulic valve lifters, commonly called stickey lifters. It can be from poor quality fuel. It can be noisy fuel injectors. It can be from a bad spark plug or plug wire.
Auto-Rx will clean up dirty hydraulic lifters. Auto-Rx will also clean up the rocker arms and valve springs, which may be playing a part in the noise.
Many times the oil warning light will flicker if the sensor is dirty. I am surprised that this would not have been manually cleaned, while they changed your oil pump. There could some blockage or resitriction in the oil flow up through the motor to the top end valve train causing this sensor to flicker.
Auto-Rx will clean this up too, as long as it is not completely plugged. Auto-Rx can only clean where oil is able to flow.
