For the working condition and lubrication characteristics of the open gear, there are relatively some requirements for the performance of the open gear lubricating oil. Open gear lubricants require proper viscosity: viscosity is the quality index of open gear lubricants. The greater the viscosity, the greater the load bearing capacity. However, if the open gear viscosity is too large, it will bring difficulties to the circulation lubrication. The stirring resistance of the open gear movement causes heat loss and heat loss. The viscosity of open gear lubricants must be suitable, especially for lubricants with extreme pressure anti-wear agents. The load-resistance performance is mainly based on extreme pressure anti-wear agents. These lubricants are not able to pursue too high viscosity. Open gear lubricants should have good thermal oxidation stability. When the open gear lubricants are working, they are strongly agitated and fully contacted with air, plus the action of moisture, impurities and metals, especially at higher temperatures. It is easier to accelerate the oxidation speed and deteriorate the properties of the lubricating oil; the open gear is corroded and worn. Open gear lubricants must have good anti-foam properties, which can be caused by the agitation of the open gears, or the agitation of the oil pump bearings of the lubricating oil circulation system and the low oil level returning to the lubricating oil tank. The oil produces foam. If the foam of the open gear lubricant cannot be quickly eliminated, it will affect the formation of the oil film on the open gear meshing surface. Open gear lubricants must have good shear stability. The viscosity of open gear lubricants is allowed to vary during use, but no significant changes are allowed at the specified temperatures. This change occurs as a result of the shearing action caused by the meshing motion of the open gear, especially under medium and heavy load conditions, the component most susceptible to shearing is the polymer. In addition, open gears have other performance requirements, such as good low temperature fluidity, compatibility with sealing materials, and storage stability.