An air compressor system, comprising: an air compressor having an air inlet and an air outlet, the air compressor configured to compress air from the air inlet and to deliver a volume of compressed air to the air outlet; an adjustable air inlet valve connected to the air inlet of the air compressor, wherein the adjustable air inlet valve is configured to be adjustable to regulate how much air can flow into the air inlet of the air compressor; a first receiver having an air inlet and an air outlet, the first receiver configured to store compressed air; a main air discharge passage connected to the air outlet of the air compressor and the air inlet of the first receiver; a first non-return valve disposed in the main air discharge passage between the air outlet of the air compressor and the air inlet of the receiver; a second receiver having an air inlet and an air outlet, the second receiver configured to separate oil from compressed air; a secondary discharge passage connected to the air inlet of the second receiver and the main air discharge passage upstream from the first non-return valve; an oil separator disposed in the first receiver; a first oil line disposed to permit oil to flow from the oil separator to the air compressor; a first oil stop valve disposed in the first oil line and configured to have an open position where oil can flow between the oil separator and the air inlet of the air compressor and a closed position where the oil cannot flow between the oil separator and the air inlet of the air compressor; a second oil line disposed to permit oil to flow from the first receiver to the air compressor; a second oil stop valve disposed in the second oil line and configured to have an open position where oil can flow from the first receiver to the air compressor and a closed position where oil cannot flow from the first receiver to the air compressor; an isolation valve disposed in the air flow between the main air discharge passage and the air inlet of the second receiver, wherein the isolation valve is configured to have an open position where air from the main air discharge passage can flow through the secondary discharge passage and a closed position where air from the main air discharge passage cannot flow through the secondary discharge passage; and a controller in communication with the adjustable air inlet valve and the isolation valve, wherein the controller is configured to take the air compressor off load by shutting the adjustable air inlet valve and opening the isolation valve, wherein the first oil stop valve and the second oil stop valve are configured to be open when the air compressor is on load and to be closed when the air compressor is off load. an air compressor having an air inlet and an air outlet, the air compressor configured to compress air from the air inlet and to deliver a volume of compressed air to the air outlet; an adjustable air inlet valve connected to the air inlet of the air compressor, wherein the adjustable air inlet valve is configured to be adjustable to regulate how much air can flow into the air inlet of the air compressor; a first receiver having an air inlet and an air outlet, the first receiver configured to store compressed air; a main air discharge passage connected to the air outlet of the air compressor and the air inlet of the first receiver; a first non-return valve disposed in the main air discharge passage between the air outlet of the air compressor and the air inlet of the receiver; a second receiver having an air inlet and an air outlet, the second receiver configured to separate oil from compressed air; a secondary discharge passage connected to the air inlet of the second receiver and the main air discharge passage upstream from the first non-return valve; an oil separator disposed in the first receiver; a first oil line disposed to permit oil to flow from the oil separator to the air compressor; a first oil stop valve disposed in the first oil line and configured to have an open position where oil can flow between the oil separator and the air inlet of the air compressor and a closed position where the oil cannot flow between the oil separator and the air inlet of the air compressor; a second oil line disposed to permit oil to flow from the first receiver to the air compressor; a second oil stop valve disposed in the second oil line and configured to have an open position where oil can flow from the first receiver to the air compressor and a closed position where oil cannot flow from the first receiver to the air compressor; an isolation valve disposed in the air flow between the main air discharge passage and the air inlet of the second receiver, wherein the isolation valve is configured to have an open position where air from the main air discharge passage can flow through the secondary discharge passage and a closed position where air from the main air discharge passage cannot flow through the secondary discharge passage; and a controller in communication with the adjustable air inlet valve and the isolation valve, wherein the controller is configured to take the air compressor off load by shutting the adjustable air inlet valve and opening the isolation valve, wherein the first oil stop valve and the second oil stop valve are configured to be open when the air compressor is on load and to be closed when the air compressor is off load.