Three 200 check valves in a series how much pressure is required to push the oil through?

To determine the pressure required to push oil through three 200 psi check valves in series, you need to consider the cumulative pressure drop across each valve. Each check valve will require at least 200 psi to open, so you would need a minimum of 600 psi to ensure that all three valves open and allow oil to flow. Additionally, you should account for any additional pressure losses due to friction or other factors in the system.