New transmission fluid aims to enhance efficiency and durability of EV drivetrains

28 April 2026  

Castrol has launched a full synthetic EV transmission fluid, ON EV Transmission Fluid W3. The company claims it can extend the life of the drivetrain system and help EVs go further on a single charge compared to mass-market EV factory-fill fluid.

The fluid has been developed specifically for electric vehicles with wet e-motors, where the electric motor operates immersed in fluid. It is designed to help optimise motor efficiency and performance by reducing friction, leading to lower operating temperatures. Castrol says that, in addition, the fluid exhibits high thermal and oxidative stability, helping maintain performance over an extended service life.

The company also states that the improved gear protection and strong thermal characteristics, combined with the fluid’s low-temperature pumpability and cold-flow properties, help to deliver reliable operation in cold climates. And that a high viscosity index means the fluid delivers consistent performance across a wide temperature range, supporting reliable operations in diverse driving conditions.

The transmission fluid’s di-electric properties include low electrical conductivity, high resistance and a high breakdown voltage, which should help to protect sensitive electrical components within the drivetrain. It is also said to provide protection against copper corrosion to aid the durability and reliability of the electric motor and associated hardware.

Vincent Panel, Head of Product & Communications – Europe at Castrol, said: “Electric vehicles demand a new generation of fluids, and that is why Castrol ON EV Transmission Fluid W3 has been formulated to meet the unique challenges of wet e-motor systems, enhancing efficiency, protection and temperature control.”

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