(1) It makes machinery suffer thermal deformation. For different thermal coefficients of the moving parts among the hydraulic elements, the less fit clearance will cause hydraulic lock and malfunction and influence the driving accuracy. As a result, the parts don't perform well.

(2) Lead to the decreased oil viscosity, increased leak, sharp decrease of the pump's volumetric efficiency and overall system efficiency. Owing to the reduced oil viscosity, the oil layer of slide valve and other moving parts will be thinner and cut open, and the frictional resistance will increase and result in severe abrasion.