The application of fluorosilicone oil in sealing and lubrication of new energy vehicle electric drive systems has formed an engineering solution centered on wide-temperature range stability, excellent insulation properties, and material compatibility. It is widely used in critical parts of high-reliability, highly integrated three-electric systems.

Core Application Scenarios
Fluorosilicone oil and its derivative fluorosilicone rubber (F-LSR) are mainly applied in the following high-risk areas of electric drive systems:

Motor bearing seals: As a dynamic sealing material, it withstands continuous operating temperatures above 150°C, preventing lubricant loss and external moisture intrusion, significantly extending bearing life;
Gearbox housing joints and end cap seals: Replacing traditional silicone or HNBR, it solves the problem of RTV silicone precipitation affecting the anti-foaming properties of the oil, achieving "no precipitation, no swelling" lifetime sealing;
High-voltage wiring harness connectors and insulation sleeves: Utilizing its low dielectric constant (≈2.1–2.8) and high volume resistivity, it ensures the insulation integrity of high-voltage circuits (>600V), preventing corona discharge and leakage;
Sensor transmission mechanisms and relay contact protection: Provides stable lubrication in micro-friction scenarios, inhibits arc erosion, and improves electrical durability. Key Performance Advantages

Wide Temperature Range Adaptability: Operating temperature range covers -60℃ to 260℃, with no solidification at low temperatures and no carbonization or volatilization at high temperatures, meeting the full operating conditions requirements of electric drive systems, including "cold start - high load - thermal runaway protection";
Chemical Inertness and Material Compatibility: No swelling or corrosion of commonly used electric drive materials such as polyimide insulation paint, epoxy resin potting compound, fluororubber, and nylon cages, avoiding system failure caused by material degradation;
Low Friction and Long Lifespan: Friction coefficient is less than 0.1, and with nano-additives, it can achieve a "lifetime lubrication" design, reducing maintenance frequency and aligning with the "high integration, low maintenance" development trend of electric drive systems;
Excellent Electrical Insulation Performance: Dielectric constant is stable at 2.1–2.8 (comparable to PTFE), with high dielectric strength and no polar by-products, ensuring no electrochemical aging risk in high-frequency PWM switching environments.
Advantages Compared to Mainstream Lubricants

Performance Indicator | Fluorosilicone Oil | PAO (Polyalphaolefin) | Ester Oil
Maximum Continuous Operating Temperature | 260℃ | 150℃ | 180℃
Hydrolysis Resistance | Excellent | Poor | Medium
Compatibility with Rubber | Excellent | Good | Fair (prone to swelling)
Dielectric Constant | 2.1–2.8 | 2.3–2.5 | 3.0–4.5
Oxidation Resistance | Excellent | Medium | Poor
Cost | High | Low | Medium
Note: Although fluorosilicone oil has a higher cost, in high-reliability electric drive systems, its total life cycle cost (including maintenance and failure rate) is more advantageous. Engineering Structure Implementation
Fluorosilicone oil is commonly incorporated into electric drive system structures in the form of fluorosilicone rubber seals or fluorosilicone-based lubricants. Typical structures include:

O-ring seals between the bearing outer ring and the bearing housing, using integrally molded fluorosilicone rubber for seamless sealing;
Skeleton-type sealing gaskets on the housing mating surfaces (such as in Tesla's design), replacing dispensing processes to improve production line cycle time and cleanliness;
Insulating potting layers inside high-voltage connectors, where the fluorosilicone oil base fills gaps, blocking the penetration of moisture and contaminants.
Current Technological Limitations and Industry Trends
Lack of publicly available aging data: Although fluorosilicone oil performs better than traditional materials in a 150℃/95%RH environment, no mainstream manufacturer has yet published accelerated aging life curves exceeding 5000 hours for its use in electric drive systems. Engineering selection still relies on internal company verification;
Lack of standards: China and the international community have not yet issued dedicated technical standards (such as GB/T or SAE J series) for the use of fluorosilicone oil in electric drive systems. Applications are mostly based on company specifications;
Trend direction: Leading companies (such as BYD, NIO, and Schaeffler) are promoting the large-scale application of fluorosilicone-based materials in 800V high-voltage platforms and oil-cooled electric drive assemblies.  Future development will move towards low-viscosity fluorosilicone oils (to improve transmission efficiency) and integration with intelligent lubrication monitoring systems.