Due to the current type of hydraulic equipment in injection molding equipment more, the same type of pump due to power, speed, pressure, flow, metal and other factors, the choice of hydraulic oil more complicated. In general, low-pressure pump HL oil can be used for medium and high pressure pump should be used HM oil. Lubrication of hydraulic oil (wear resistance) on the three major anti-wear pump sequence is vane pump> piston pump> gear pump. Vane pump hydraulic system for the main pump regardless of the size of the oil should choose HM as well, because the blade vane and stator contact and movement between the form of easy to wear, the steel friction pair of steel materials most suitable for the use of high zinc HM anti-wear hydraulic oil. HM oil and HL oil are available for low-pressure piston pumps, and zinc-containing HM oils are used for high-pressure piston pumps. However, high-zinc anti-wear agents cause corrosive wear when the plunger pump contains bronze and silver-plated parts. To use ash-free or low zinc anti-wear hydraulic oil. For gear pumps, the use of HH, HL, HM oil can be, but high performance gear pump should be HM oil. For combination systems such as vane pumps and other pump combinations, the vane pump should be the main choice. When the other pumps are piston pumps, the selected oil should also be accepted by the piston pump. Taken together, HL oil is usually preferred for axial piston pumps, but not for vane pumps, and high zinc HM oils are suitable for all types of vane pumps. Ashless HM oil is suitable for axial piston pumps containing copper and silver parts, but also for medium and low pressure vane pumps, but not for high pressure vane pumps. Low zinc HM oil is suitable for a wide range, both for medium and high pressure vane pumps, but also for copper and copper parts of the plunger pump. Reasonable selection of hydraulic fluid is only the starting point for the normal operation of hydraulic equipment. During the operation of the system, the performance of hydraulic fluid should be promptly checked to ensure proper maintenance in time so as to prolong the service life of hydraulic fluid, system and components, Avoid media failure caused by the system, or even an accident. Hydraulic oil life (ie, oil change period) due to the selection of hydraulic oil varieties, working conditions and system operating conditions are different, but there are significant differences, the election of oil is reasonable, good oil quality, the hydraulic system and hydraulic fluid Good maintenance and management, the oil change period can be greatly extended.