Oxidation Stable EV Transmission Fluids

Electric traction drive system with optimized cooling and lubrication for electric vehicles. The system has both active and passive cooling/lubrication circuits. In normal operation, an electric pump actively cools the electric machine. But if the pump fails or active cooling is not needed, a passive circuit takes over using oil pressure from the transmission components like gears and bearings. This ensures fail-safe lubrication and optimizes efficiency/thermal performance by using the right cooling circuit for each operating condition.

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Lubricating oil composition for electric vehicle transmissions that balances wear protection with good copper corrosion resistance, sufficient volume resistivity, and good hot surface deposit control. The composition contains a sulfur-based additive with a thiadiazole and a sulfurized polyolefin, along with phosphorus-containing anti-wear additives. The sulfur-based additive provides wear protection and helps prevent corrosion. The phosphorus additives provide wear protection without contributing to corrosion. The oil also has specific viscosity and volume resistivity ranges.

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Lubricating oil composition for electric vehicles, comprising a major amount of lubricating oil, a phosphorus-containing additive, and a sulfur-containing additive selected from thiadiazole, dithiadiazole, dimercaptodithiadiazole, and derivatives thereof, wherein the sulfur-containing additive is soluble in the lubricating oil without the need for a dispersant additive.

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A low-traction and high-pressure viscosity fluid formulation for electric vehicle drive units and drivelines that provides improved efficiency, gear protection, and motor cooling through optimized boundary and mixed lubrication regimes. The formulation combines low-friction molecules with higher-viscosity secondary molecules to achieve reduced friction and traction, while maintaining high-temperature stability and hydrolytic resistance.

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Melamine-based corrosion inhibitors for lubricants that provide improved copper corrosion protection compared to traditional tolyltriazole additives. The melamine derivatives are oil-soluble compounds formed by reacting hydrocarbyl-substituted succinic acids or anhydrides with melamine. The reaction involves using a molar excess of the succinic acid or anhydride relative to the melamine. The resulting melamine succinimide or acid/amide compounds have structures like Formula I. These melamine derivatives provide copper corrosion inhibition in lubricants like transmission fluids, axle fluids, and gears without the use of tolyltriazole.

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Base oil composition for electric vehicle fluids comprising a blend of poly-alpha-olefins (PAO) with different viscosities, and an electric vehicle fluid prepared using the base oil. The base oil is formulated by mixing PAO components with a viscosity range of 2-20 cSt, and the electric vehicle fluid is prepared by adding functional additives to the base oil under controlled temperature and mixing conditions. The base oil composition provides improved thermal conductivity, oxidation stability, and lubrication performance for electric vehicle applications.

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Lubricating oil compositions with enhanced fatigue protection, particularly suitable for functional fluids and electric vehicle applications, comprising 0.001-1.5% anti-fatigue additive and sulfonate detergent, with reduced levels of sulfur-containing compounds, such as metal sulfurized phenates, and optionally glycerol, which imparts improved fatigue performance without compromising anti-wear properties.

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A lubricant fluid for electric vehicle transmissions that combines biodegradable ester base oils with a carefully selected additive package to provide optimal performance in high-torque, high-speed, and low-temperature operating conditions. The fluid features a unique blend of ester base oils, including a high-viscosity complex ester, along with a specialized anti-foam additive and a friction modifier. The formulation is designed to meet the specific demands of electric vehicle transmissions, including low electrical conductivity to prevent dielectric breakdowns.

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Electric vehicle transmission fluid formulation that provides high performance under extreme pressure and high load conditions while maintaining compatibility with yellow metals and electrical components. The fluid formulation includes an oxidation inhibitor, anti-wear additive, and copper corrosion protection, and exhibits low electrical conductivity to prevent static electricity discharge. The formulation is designed to meet the unique demands of electric vehicle transmissions in both light and heavy duty applications.

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Lubricant composition for electric vehicle propulsion systems that improves antiwear and anticorrosion properties by combining triazole corrosion inhibitors with amine- and sulfur-based antiwear additives. The triazole compounds like tolyltriazole prevent corrosion of metal components while the amine-sulfur additives like dimercaptothiadiazoles reduce wear. This combination provides simultaneous wear and corrosion protection for electric vehicle motors, bearings, and transmissions.

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A lubricant composition for electric and hybrid vehicle motors, comprising a base oil blend of polyalkylene glycol (PAG), poly-alpha-olefin (PAO), and ester, with an additive package including a sulfur-based extreme pressure agent. The PAG provides thermal stability and low viscosity, while the PAO and ester enhance solubility and compatibility with the extreme pressure agent. The composition is optimized for electric motor applications, avoiding additives typically used in conventional lubricants that can degrade performance.

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Base oil for automotive transmission and gear systems that provides superior traction and thermal management properties in electric vehicles. The base oil comprises a unique blend of compounds optimized for electric vehicle powertrains, featuring improved oxidation stability, thermal conductivity, and viscosity characteristics. The formulation enables enhanced traction performance in electric vehicles, particularly in the high-temperature regions of the powertrain, while maintaining reliable low-friction operation in the low-temperature conditions of the battery pack and other components.

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A lubricating fluid for electric motor systems in hybrid and electric vehicles, comprising a lubricating oil and additives, including a succinimide dispersant, a sulfur-providing additive, and a detergent system, that provides improved wear protection, oxidative stability, and electrical conductivity while maintaining low viscosity. The fluid is formulated with a specific combination of additives that balance antiwear, friction, and corrosion performance while minimizing electrical conductivity.

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A lubricating fluid composition for electric drives that prevents corrosion of electrical components while maintaining high efficiency in transmissions. The composition comprises 10-88% by weight of a low-viscosity synthetic oil, 0.1-5% by weight of a borated succinimide dispersant, 0.1-5% by weight of a 2,5-alkyl-thiadiazole compound, and 0.1-5% by weight of a phosphorus-containing additive. The composition has a dynamic viscosity of 0.8-4.0 mm2/s at 100°C and is suitable for use in electric motors, transmissions, and battery-operated vehicles.

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When the electric motor (EM) of a hybrid electric vehicle (HEV) is located inside the transmission housing, the cooling performance and the electrical compatibility of the automatic transmission fluids (ATFs) play a more relevant role. These two features depend on both physicochemical and thermal properties of the lubricant, but these properties change with the aging or oxidation of the ATF. This work studies the influence of external factors like temperature, time, and air exposition on the oxidation of three commercial ATFs and how this oxidation affects properties such as density, viscosity, thermal conductivity, heat capacity, ionicity, and some cooling-related figures-of-merit (FOMs) of the fluids, and thus, their cooling performance and electrical compatibility. The results showed that the molecular structure of the ATFs has more influence on thermal conductivity and heat capacity than on density, and hardly affects the FOMs of the fresh lubricants. Those ATFs formulated with API Group III base oils resulted in better cooling properties than the ATF with base oils from API Grou... Read More

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Lubricating oil composition for transmissions that achieves both low viscosity and high gear protection while preventing copper corrosion and maintaining oxidation stability. The composition combines a sulfur-based extreme pressure agent with a phosphorus-based extreme pressure agent, both having specific molecular structures, to create a protective oil film on metal surfaces. This film suppresses metal-to-metal contact and solid phase fusion, preventing gear damage such as scuffing. The composition is suitable for use in transmissions where gear protection is critical, particularly in applications where low viscosity lubricants are required for fuel efficiency.

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A lubricant base stock with improved thermal stability and oxidation resistance, comprising a high viscosity Group II base stock with a kinematic viscosity at 100°C of 29 cSt to 32 cSt or more, and a sulfur content of less than 0.03 wt %. The base stock is produced by catalytic processing of C3 deasphalted oils, and exhibits superior performance in oxidation tests and haze formation resistance compared to conventional base stocks.

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Fluids for electric vehicles that have improved performance compared to traditional lubricants. The fluids contain base stocks with specific properties like high viscosity index, high saturates content, and low aromatics content. The base stocks are derived from deasphalted oil using processes like hydroprocessing and solvent extraction. This allows forming high viscosity Group II base stocks with lower pour points, better color, and equivalent viscosity index compared to Group I stocks. The fluids also have improved thermal conductivity and specific heat capacity for cooling electric machines and batteries.

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A lubricant base stock with improved thermal stability and oxidation resistance, comprising a high viscosity Group II base stock with a kinematic viscosity at 100°C of 29 cSt to 32 cSt or more, and a composition of greater than or equal to 90 wt % saturates, less than or equal to 10 wt % aromatics, and a sum of terminal/pendant propyl groups and terminal/pendant ethyl groups of at least 1.7 per 100 carbon atoms. The base stock is suitable for use in low-temperature environments and can be formulated into lubricants with enhanced deposit resistance and oxidation stability.

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A lubricating composition for electric and hybrid vehicles that combines lubrication and cooling properties. The composition comprises a base oil and additives such as antiwear, antioxidant, and dispersant agents, with specific concentration ranges of boron (≤100 ppm) and nitrogen (100-500 ppm). The composition is designed to provide improved durability and electrical resistivity for electric motor and hybrid vehicle applications, including cooling of power electronics, rotors, and stators, as well as lubrication of bearings and gearboxes.

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A lubricating oil composition for electric drive units that combines gear oil and motor oil functions, featuring high extreme pressure resistance, durability, and wear resistance, along with high volume resistivity. The composition contains a phosphite ester derivative with a sulfur-substituted alkyl group and a thiadiazole derivative, which are blended with a base oil. This unique combination enables the lubricating oil to meet the demanding requirements of electric drive units, including miniaturized gearboxes and high-force tooth surfaces.

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A lubricating oil composition for electric motors and transmissions that maintains electrical insulation and copper corrosion inhibition performance even after oxidative degradation. The composition comprises a lubricant base oil, a nitrogen-containing oiliness agent-based friction modifier, a calcium detergent, a phosphite ester, an ashless dispersant, and an antioxidant. The composition has a kinematic viscosity at 100°C of 1.8 to 4.0 mm2/s, and exhibits improved long-term stability of electrical insulation and copper corrosion inhibition performance compared to conventional lubricating oils.

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Lubricant composition for electric vehicle propulsion systems that combines succinimide compounds with amine-based and sulfur-based antiwear additives to prevent corrosion and wear on moving parts. The succinimide compounds, such as polyisobutylene succinimides, are used as anticorrosion additives to mitigate the corrosive effects of amine-based and sulfur-based antiwear additives, while maintaining their wear-reducing properties. The composition is suitable for lubricating electric motors, power electronics, and transmission components in electric and hybrid vehicles.

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Placing an electric motor (EM) inside the transmission housing of a hybrid electric vehicle (HEV) implies that the automatic transmission fluid (ATF) needs to accomplish additional requirements. Among these requirements, electrical compatibility is of critical significance. This study investigated the influences of the additive concentrations of three commercial ATFs on their electrical compatibilities and tribological performances. Two variations of each ATF with different concentrations of the original additive packages were prepared. The viscosity, electrical conductivity, permittivity, resistivity, dielectric dissipation factor, breakdown voltage, and tribological performance of the nine resulting ATFs were measured. All the ATFs were found to be electrically compatible and showed dissipative performance and sufficiently high breakdown voltage, even at increasing additive concentrations. The tribological performances of the ATFs formulated with the API (American Petroleum Institute) Group III base oils had improved wear reduction at the highest additive concentrations; the better... Read More

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A lubricant for electric vehicles comprising a base oil selected from carboxylic acid esters, such as 2-ethylhexyl oleate, that provides controlled electrical conductivity, heat conductivity, wear protection, oxidation stability, deposit control, and corrosion inhibition over the lifetime of the lubricant. The carboxylic acid ester base oil enables the lubricant to maintain its lubricating properties despite exposure to high surface temperatures of electrical components in electric and hybrid vehicles.

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Lubricants for electric and hybrid vehicles that provide improved efficiency and durability in drive systems, including transmissions and axles. The lubricants comprise a base oil, a gear oil additive, and a molybdenum dialkyldithiocarbamate additive, which provides enhanced protection against electrical corrosion and wear. The lubricants also enable diagnostic and design tools for electric vehicle transmissions and engines by indicating application conditions through color changes.

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A heat transfer system and method employing a dielectric oleaginous heat transfer fluid with low electrical conductivity, low flammability, and low freeze point for cooling electrical componentry. The fluid, comprising isoparaffins, esters, ethers, or alkylated aromatic oils, is free of cyclic structures and has a kinematic viscosity of 0.7-7.0 cSt at 100°C and a flash point of at least 50°C. The fluid is used in an immersion cooling system for electrical componentry, including battery packs in electric vehicles, where it provides excellent peak temperature reduction and prevents electrical shock.

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The most common degradation process of insulating liquids is oxidation and each type of insulating liquid has its specificities. This paper reviews the mechanisms of oxidation in natural ester insulating liquids doing a comparison with same degradation process in mineral oil. Oxidation by-products in mineral oil produces acids (corrosive to other transformer material) and sludge (which can block cooling ducts). In turn, oxidation by-products in natural ester does not produce sludge, only increases liquid viscosity. An important assessment done in this paper it is regarding the test method for evaluation of oxidation stability in some natural ester international standards, beyond the IEC 62770. National standards in Brazil, Colombia, Ecuador and Mexico have defined test parameters and acceptance criteria to qualify the oxidation stability of new natural esters. The most common types of insulating liquid preservation systems will be reviewed in the paper with focus in analyze the role in preserving the liquid quality by preventing contaminants, mainly the oxygen. A well formulated natu... Read More

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A durable lubricating fluid for electric motors and hybrid-electric motors that maintains low electrical conductivity over its lifespan. The fluid comprises a lubricating oil, a thiadiazole or derivative providing sulfur and nitrogen, an amine salt of a phosphoric acid ester providing phosphorus and nitrogen, and a sulfur-to-phosphorus-to-nitrogen weight ratio of at least 2.3. This composition delivers wear protection while maintaining low electrical conductivity, making it suitable for electrified vehicles.

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A transmission fluid composition for hybrid and fully electric vehicles that provides lubrication, cooling, and electrical insulation to mechanical and electrical components. The composition comprises a major amount of a lubricating oil basestock and a minor amount of an additive package containing a phosphorus-containing compound, a calcium salicylate detergent, and other additives. The composition achieves a balance between electrical insulation, wear protection, and low viscosity, enabling its use in hybrid and fully electric transmissions where conventional lubricants are insufficient.

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A lubricating fluid for electric motor systems that provides wear protection, copper corrosion inhibition, and high electrical resistivity. The fluid comprises a base oil and a phosphorylated succinimide dispersant with 2-3.5 wt% phosphorus, which delivers 650 ppm or less phosphorus to the fluid. The fluid has a kinematic viscosity of 3-6.5 cSt at 100°C and a resistivity of at least 50 MΩ·m after aging at 150°C.

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A lubricating oil composition for electric motors and generators, comprising a base oil, a neutral phosphorus compound, an acidic phosphorus compound, a sulfur compound, and a metal salt selected from metal sulfonates, salicylates, and phenates. The composition has improved electrical insulation, wear resistance, and copper corrosion prevention, making it suitable for use in hybrid and electric vehicles.

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The in electrical vehicles, where the electric motor is inside the transmissielectrical compatibility of the automatic transmission fluids (ATFs) is very important on and in contact with the ATF. This work studies the influence of factors like temperature, time, and air exposition on the oxidation of three ATFs and their changes in electrical conductivity. The results showed that the higher content of additive the lower variations of electrical conductivity with the oxidation; the measurements of electrical conductivity are better than FT-IR ones for monitoring oil thermo-oxidative degradation at initial periods; the conventional ATFs could maintain good electrical compatibility in electrified drivelines, although their materials compatibility and copper corrosion protection of electrical components should be also tested.

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Increasing automotive powertrain electrification is impacting drivetrain complexity and the profiles of the fluids needed. Since the millennium, drivetrain fluid viscosities have been reduced for better efficiency, but this new challenge is driving them to unprecedented low levels. This paper assesses some of the potential implications of ultra-low viscosity fluids on drivetrain functionality and durability. Model formulations have been prepared from a variety of base fluids combined with additive packages. These have been evaluated in typical automotive drivetrain rig tests, as well as with some selected functional tests. In addition, the thermo-oxidative stability and electrical and thermal properties of the fluids were compared. Based on the results, the impact of low viscosity fluids on drivetrain functionality and durability varies depending on the performance parameter evaluated. For example, gear scuffing and bearing wear is highly dependent on additives, whilst gear and bearing fatigue is mainly affected by fluid viscosity. However, by carefully balancing base fluids and addi... Read More

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Lubricating compositions for electric and hybrid-electric vehicle transmissions that provide simultaneous lubricating, electrical, and thermal performance. The compositions comprise a solvent system of a base oil blended with a branched diester, combined with low molecular weight poly(meth)acrylate copolymers. The branched diester component is a reaction product of dicarboxylic acids and alcohols with specific chain lengths. The copolymers have a weight average molecular weight of 50,000 g/mol or less and a polydispersity index of 1 to 2. The compositions achieve electrical conductivity of 80,000 pS/m or less and thermal conductivity of 134 mW/m*K or more.

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A lubricating oil composition for electric vehicles, hybrid vehicles, and plug-in hybrid vehicles with electric motors and/or generators, comprising a base oil, a phosphorus-containing antiwear additive, a corrosion inhibitor, and a sulfur-based extreme pressure additive, wherein the composition is substantially free of metal compounds such as calcium, molybdenum, and zinc, and demonstrates high volume resistivity, wear protection, and copper corrosion resistance.

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The rapid growth of electrified vehicles and increased electrical componentry in the powertrain has resulted in a requirement for new, tailored lubricating fluid technologies

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Functional fluids for automotive transmissions, electric motors, and battery packs, comprising a low-viscosity, low-volatility polyalpha-olefin (PAO) base stock made by oligomerization of linear alpha-olefin monomers in the presence of a metallocene catalyst system. The PAO base stock has a kinematic viscosity at 100°C of 3.0-4.5 cSt and a Noack volatility of ≤15%. The functional fluid is particularly suitable for high-performance transmissions in hybrid vehicles, where low viscosity and low volatility are critical for thermal management and lubrication.

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Lubricant composition for electric or hybrid vehicle propulsion systems that uses phosphorus compounds free of sulfur and amine functions as anti-wear and extreme pressure additives. The phosphorus compounds, such as triaryl phosphate esters, provide wear protection without inducing corrosion on metal surfaces, unlike conventional additives. The lubricant composition is suitable for lubricating electric motors, power electronics, bearings, and transmissions in electric or hybrid vehicles.

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A lubricating oil composition for electric vehicles and hybrid vehicles that combines gear, clutch, cooling, and electrical insulation properties. The composition comprises a base oil with a synthetic oil component having a kinematic viscosity of 1.0-10.0 mm^2/s at 100°C, blended with a polyamide and/or polyol ester additive. The composition exhibits excellent performance in gear and clutch applications, while also providing cooling and electrical insulation properties suitable for electric vehicle and hybrid vehicle applications.

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A lubricating oil composition for transmissions that achieves both high viscosity index and high shear stability, enabling improved fuel efficiency. The composition comprises a mineral oil and a specific type of polymethacrylate with an oxygen-containing functional group, which provides enhanced viscosity index and shear stability compared to conventional polymethacrylates. The composition is particularly suitable for transmissions in gasoline, hybrid, and electric vehicles.

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A lubricating oil composition for electric motors and transmissions that provides electrical insulation, anti-seizure performance, copper corrosion inhibition, and anti-fatigue performance. The composition comprises a lubricating base oil, a poly(meth)acrylate viscosity index improver, a phosphite ester compound, a thiadiazole compound, and a calcium salicylate detergent. The composition has a specific sulfur-to-phosphorus ratio and meets viscosity requirements for both electric motors and transmissions.

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A lubricating oil composition for automatic transmissions comprising 55-85% Fischer-Tropsch synthetic oil (2-4 mm2/s at 100°C), 1-10% olefin copolymer (150-1000 mm2/s at 100°C), and a polymethacrylate (10,000-50,000 Mw) to achieve a viscosity index of at least 190, a Brookfield viscosity of ≤6000 mPa·s at -40°C, a 100°C kinematic viscosity of 6-7 mm2/s, and a KRL shear stability of ≤3% reduction.

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A lubricating and cooling composition for electric vehicle drive systems, comprising a base oil with a kinematic viscosity of 1.5-8 mm^2/s, thickened with polymers such as ester polymers, styrene-butadiene-isoprene copolymers, and polyacrylates. The composition has a non-Newtonian fluid behavior and can be used for both lubrication and cooling of electric motors, batteries, and transmissions in electric and hybrid vehicles.

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Lubricating compositions for driveline applications, such as transmissions, gearboxes, and axles, that provide antiwear, extreme pressure, and load-bearing capacity while meeting stringent sulfur and phosphorus limits. The compositions contain a novel additive, 5-(methylthio)-3,4-thiadiazole-2(3H)-thione, which enhances gear scuffing resistance and provides improved performance in FZG tests. The additive is soluble in lubricating oils without the need for premixing with dispersants, unlike conventional additives. The compositions can be formulated with a range of base oils, including Group I, II, III, IV, and V synthetic oils, and can be used in manual and automatic transmissions, clutches, gearboxes, axles, and differentials.

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A lubricant composition for hybrid electric vehicle transmissions, comprising an oil of lubricating viscosity, 0.3-2.0 wt% of at least one borate ester, and a phosphorus-containing compound delivering 100-450 ppm of phosphorus. The composition provides low electrical conductivity, improved lubrication, and corrosion protection for electric motor components while maintaining low viscosity for fuel efficiency.

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Lubricating oil composition for hybrid and electric vehicles, comprising a base oil, neutral and acidic phosphorus compounds, a sulfur compound, and an organic molybdenum compound, which provides improved lubricity and cooling properties for electric motors and gear reducers in hybrid and electric vehicles.

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The rapid growth of electrified vehicles and increased electrical componentry in the powertrain has resulted in a requirement for new, tailored lubricating fluid technologies

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