Leaks in general and hydraulic leaks in specific are one of the major failure modes for mobile equipment. In-plant leak rates may range from 1% to 25%, while field leaks may range from 1% to 13% depending on the complexity of the system, assembly process, and parts quality. In this paper, the main potential leak causes are discussed and the performance of different types of fittings is compared, including JIC 37 flare fittings, O-ring boss seal, and O-ring face seal. Several potential improvement actions related to assembly process, torque specifications, and quality of manufactured fittings are proposed to reduce leaks. Among the many benefits leak reduction will result in improved customer safety and satisfaction, assembly down time reduction, cost and warranty reduction, and environmental impact reduction.