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Reducing powertrain losses is an important technical challenge to further improve the efficiency of electric vehicles as part of measures toward achieving carbon neutrality. One effective method of accomplishing this goal is to reduce the viscosity of transaxle lubricating oil. However, it is generally known that lowering viscosity can cause durability issues such as wear and seizure if the thickness of the lubricating oil film on metal sliding surfaces is insufficient. In gears and bearings, reducing the oil film thickness can increase direct contact with the base metal and may cause surface fatigue peeling. A new additive formulation for lubricating oil specifically for electrified vehicles has been designed in anticipation of the wider adoption of such vehicles in the future. The result has been a new transaxle fluid that ensures unit durability while reducing viscosity of 40°C to 12.2[mm2/sec].

In electric vehicles (EVs), drivetrain lubricants (EV fluids) are often relied upon to aid in cooling the motors. In such cases, the lubricants must provide high cooling performance. They should also improve the efficiency of the transmissions and reduction gearboxes in EV drivetrains. Both requirements can be met by lowering the viscosity of the fluid. This effectively improves the heat transfer coefficient and also helps increase efficiency by reducing churning loss. However, a viscosity that is too low can negatively affect the fatigue life of mechanical parts such as gears and bearings. To solve the issues associated with lower viscosities, we optimized the anti-wear agents, dispersants, and other additives to develop formulations specially designed for EV drivetrains. The result are lubricants that provide excellent extreme pressure properties and protection for drivetrain components despite their lower viscosities.