Castrol has launched the ON EV Transmission Fluid W3, a full synthetic lubricant for electric vehicles with wet e-motor systems. Designed to reduce operating temperatures, improve drivetrain efficiency, and provide dielectric and corrosion protection, the fluid is compatible with EVs from brands including Polestar, Rivian, Tesla, and Volvo.
Castrol, a bp group company, has launched Castrol ON EV Transmission Fluid W3, a full synthetic transmission fluid developed specifically for electric vehicles (EVs) fitted with wet e-motors — systems in which the electric motor operates immersed in fluid.
The product is engineered for use in EVs from Leapmotor, MG, Polestar, Rivian, Tesla, and Volvo, among others. According to Castrol, the fluid reduces friction to help lower operating temperatures and improve motor efficiency, with the company claiming it enables EVs to travel further on a single charge compared with mass-market factory-fill fluid, based on its own bespoke testing. No independent test data or specific performance figures were provided.
The fluid’s dielectric properties — including low electrical conductivity, high resistance, and a high breakdown voltage — are designed to protect sensitive electrical components within the drivetrain. It also offers copper corrosion protection and is formulated for low-temperature pumpability and cold-flow performance, intended to maintain reliable operation in cold climates. A high viscosity index is said to ensure consistent performance across a wide temperature range.
Vincent Panel, head of product and communications for Europe at Castrol, says: “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.”
Castrol ON EV Transmission Fluid W3 sits within the brand’s wider Castrol ON range, which encompasses EV-specific fluids, greases, and thermal management solutions. Castrol advises vehicle owners and service professionals to consult vehicle manufacturer recommendations before selecting a fluid for a specific application.
