Across vehicle types, many lubricant applications retain broadly similar performance requirements regardless of drivetrain. Brake fluids, shock absorber fluids and greases used in doors, locks and wheel bearings are largely unaffected by the transition from internal combustion engines to electrified powertrains. Other fluids face substantially different requirements in battery electric vehicles, hybrids and conventional ICE vehicles.
Some lubricants are specific to particular vehicle architectures while others serve similar components operating under very different thermal, electrical and mechanical conditions. The growing complexity of electrified powertrains is therefore creating demand for formulations tailored to specific applications.
Key Technical Challenges
Electrification introduces several challenges for lubricant developers. These include thermal management of electric motors and batteries, exposure to electric fields and currents, copper corrosion and compatibility with the polymers, elastomers and insulation materials used in electrified powertrains.
Other requirements include low and stable viscosity, friction control, oxidation resistance, material compatibility and durability over extended service intervals. Electric motors can operate at much higher rotational speeds than conventional engines and integrated electric drive units can place lubricants in direct contact with copper windings and other electrical components.
Many current electrified vehicles continue to use fluids derived from technologies developed for conventional vehicles, particularly in applications where existing formulations meet the required specifications. At the same time, dedicated fluids have emerged for electric drive units and other electrified components as OEM requirements have become more specific.
Viscosity and Base Oil Requirements
Lower viscosity remains an important development trend across automotive lubricants as manufacturers seek to reduce frictional losses and improve energy efficiency. In electrified powertrains, low viscosity can also help manage the higher rotational speeds of electric motors and improve lubricant circulation and heat transfer.
Reducing viscosity, however, places greater demands on the formulation. Lubricants must maintain adequate film strength, wear protection, oxidation stability and volatility performance across a wide temperature range. Base oil selection is therefore increasingly important, with Group III, polyalphaolefin and ester base stocks among the options used in higher-performance formulations. The appropriate base oil depends on the application and cannot be reduced to a simple shift away from mineral oil.
Electrical Properties
Electrical properties have become an important consideration for lubricants used in electrified drivetrains. Electric drive units can expose lubricants to electric fields and, in some designs, bring the fluid into direct contact with motor windings and other electrical components.
Formulators therefore have to control properties including electrical conductivity, resistivity and dielectric strength. Excessive conductivity can increase the risk of current leakage while excessive electrical insulation can contribute to charge accumulation and electrostatic discharge in some operating conditions.
Electrical behaviour is affected by factors including temperature, lubricant composition, additive chemistry and aging. Research and OEM specifications increasingly assess the electrical properties of both fresh and aged fluids, making long-term electrical stability an important part of EV lubricant development.
Copper Corrosion Risks
Copper compatibility is a particular concern where electric motors are integrated into transmissions or drive units and copper windings come into contact with the lubricant.
Corrosion can damage copper components and generate conductive deposits that may compromise electrical insulation. Conventional copper corrosion tests such as ASTM D130 remain useful but do not necessarily reproduce the combination of electrical, thermal and chemical stresses found in electrified powertrains. The industry has consequently developed additional test methods, including wire corrosion and conductive deposit tests, to better assess these risks.
Lubricant chemistry must also balance copper protection with other performance requirements. Some traditional antiwear and extreme-pressure chemistries contain sulfur or phosphorus compounds that can present compatibility challenges, so formulators must balance corrosion protection with wear performance and other specification requirements.
EV-Specific Lubricants
The transition to electrified vehicles is creating a growing market for application-specific fluids, although the shift is gradual. Electric drive units, integrated motors and high-speed transmissions impose requirements that differ from those of conventional transmissions and engines, particularly in electrical properties, thermal management, copper compatibility and materials compatibility.
There is also considerable variation between vehicle architectures. Motor position, gear design, cooling strategy, operating speed and the extent to which lubricant comes into contact with electrical components all influence fluid requirements. This means that the industry is still developing and refining specifications and test methods for many electrified applications.
Hybrids
Hybrid vehicles combine conventional engine lubrication requirements with the demands of electric propulsion. Their engines can operate intermittently and at different temperature profiles from those in conventional vehicles, while some hybrid systems integrate electric motors directly into transmissions.
Lower engine temperatures and shorter or intermittent operating cycles can increase the importance of water and fuel dilution management. Hybrid systems also introduce additional materials and components, including electrical insulation, seals and polymers that may come into contact with lubricants.
As a result, hybrid lubricants must balance conventional engine or transmission requirements with the electrical, thermal and material compatibility demands created by electrification.
Thermal Management and Cooling
BEVs eliminate engine oil as a major lubricant category, but they continue to require transmission and gear lubricants, greases and other fluids. Depending on vehicle architecture, fluids may also play a direct role in cooling electric motors, gears and other drivetrain components.
Thermal management is becoming increasingly important as manufacturers increase battery energy density, charging power and electric motor performance. Lubricants used in electric drive units can contribute to heat removal as well as friction and wear control, creating demand for fluids with appropriate thermal properties alongside low viscosity and high-temperature stability.
Battery cooling is a separate application with its own technical requirements. Conventional water-glycol systems remain widely used, while manufacturers and suppliers are investigating direct and dielectric cooling approaches as battery designs and charging requirements evolve. The resulting opportunities extend beyond conventional lubrication into the broader market for thermal-management fluid