A method of operating a hydraulic system and hydraulic system for raising and lowering a boom in extreme climates. When the temperature is below a low temperature the system is operated open center while a variable displacement pump providing a constant flow of hydraulic fluid. When the temperature is between the low temperature and a moderate temperature the variable displacement pump provides at least a minimum flow of hydraulic fluid to the system, and the minimum flow decreases linearly with an increase of the temperature. When the temperature is above the moderate temperature, the system is operated closed center while maintaining at least a system pressure when in neutral and wherein the variable displacement pump provides hydraulic fluid to the actuator when a control valve is actuated.