1. Chemical Resistance
 Due to its fully fluorinated carbon chain structure, fluororubber exhibits near-inertness to aromatic hydrocarbons (such as benzene and toluene) and strong oxidants (such as peroxides) in fuel. Typical test data shows that after immersion in 120°C fuel for 1000 hours, the volume expansion of fluororubber is less than 5%, while that of fluorosilicone is approximately 8%-12%. This property makes fluororubber a preferred material for high-pressure injector seals.
 
The silane-oxygen backbone of fluorosilicone provides it with superior compatibility with polar solvents, such as the ethanol in ethanol-based gasoline. For example, in an environment with E10 ethanol-based gasoline, fluorosilicone can retain over 85% of its tensile strength, while fluororubber may experience a drop in strength to 70% due to ethanol penetration, which can disrupt the crosslinking network.
 
2. Temperature Compatibility 
The upper continuous operating temperature limit of fluororubber (250°C) is significantly higher than that of fluorosilicone (200°C), making it suitable for high-temperature sealing applications around turbocharged engines. However, its low-temperature performance is significantly limited: at -20°C, its hardness rises to over 90 Shore A, potentially leading to seal failure.
 
Fluorosilicone maintains flexibility below 50 Shore A at -60°C, making it an ideal choice for fuel line seals in cold-weather vehicles. For example, fuel sensor hoses for vehicles used in extreme cold regions in Russia commonly utilize a fluorosilicone/nylon composite structure to achieve both low-temperature sealing and mechanical strength. 
  
3. Balancing Mechanical Performance and Economic Efficiency
 Fluoroelastomers offer far superior tensile strength (20 MPa grade) and abrasion resistance (ASTM D5963 wear volume <50 mm³) to fluorosilicone, making them suitable for dynamic friction components (such as fuel pump shaft seals). However, their processing energy consumption is 15%-20% higher than that of fluorosilicone, and they require a secondary vulcanization process.
 
Fluorosilicone can be adjusted to a hardness range of 30-80 Shore A by adding fumed silica, making it more suitable for injection molding of custom-shaped seals. A German automaker uses 55 Shore A fluorosilicone in its fuel quick-connect connector seals, reducing installation force by 40% while maintaining sealing reliability.
 
4. Comparison of Typical Application Scenarios
Fluororubber's leading applications: High-pressure seals in fuel injection systems and turbocharger oil return lines.
Fluororubicin's advantageous applications: Oil float seals requiring high compatibility with ethanol gasoline and sensor harness sheaths subject to frequent flexing.