Fluorosilicone oil and phenyl silicone oil each have advantages in chemical resistance and temperature resistance. Fluorosilicone oil performs better in resistance to chemical solvents and fuels, while phenyl silicone oil has advantages in high-temperature and radiation resistance. The choice depends on the specific application scenario.
Phenyl Silicone Oil

I. Comparison of Chemical Resistance Properties
1. Chemical Resistance Characteristics of Fluorosilicone Oil
Oil and Solvent Resistance: The trifluoropropyl (-CF₃) group in the fluorosilicone oil molecule forms a low-surface-energy protective layer, giving it excellent stability against hydrocarbon solvents and strong oxidizing agents.  Its surface tension is as low as 20-25 mN/m, approximately 30% lower than ordinary silicone oil.
Resistance to Special Media: It maintains stable physical properties in a 500-hour methanol gasoline immersion test, shows zero corrosion to fluorine-containing coolant (HEXAFLUO BoreafTM), and is suitable for compressor and valve lubrication in contact with liquid oxygen, oxygen, corrosive and oxidizing gases.
Chemical Stability: The strong electronegativity of the fluorine atom in the molecule gives it excellent oxidation resistance and chemical inertness, effectively resisting free radical-initiated chain oxidation reactions.

2. Chemical Resistance Characteristics of Phenyl Silicone Oil
Organic Solvent Compatibility: The solubility of phenyl silicone oil in organic solvents increases with increasing phenyl content, but its oil resistance is not as good as fluorosilicone oil, and its resistance to polar solvents (such as alcohol and acetone) is limited.
Special Advantages: Significant hydrophobic function, excellent dielectric properties, volume resistivity ≥1×10¹⁴ Ω·cm (25℃), and dielectric loss tangent ≤1×10⁻³⁹.
Compatibility Characteristics: Better compatibility with cosmetic ingredients than methyl silicone oil, stable to heat and ultraviolet light, and has a unique gloss. 3. Key Differences in Medium Resistance Performance
Fuel Environment: After prolonged immersion in aviation fuel, gasoline, diesel, and other environments, fluorosilicone oil exhibits a volume change rate of ≤25% (23℃ × 24 hours), while phenyl silicone oil can have a volume change rate of 30-40% under similar conditions.
Strong Chemical Corrosion Environment: Fluorosilicone oil performs better in strong acid and alkali environments and fluorine-containing media, making it particularly suitable for extreme chemical environments such as chemical processing and semiconductor etching processes.
Electronic Applications: Phenyl silicone oil is more suitable as an insulating medium in the electronics field due to its superior dielectric constant (2.6-3.0) and breakdown strength (>45KV/2.5 mm).

II. Comparison of Temperature Resistance Performance
1. Temperature Resistance Characteristics of Fluorosilicone Oil
Operating Temperature Range: -60℃ to 200℃ (some models can reach 250℃), remaining soft and not hardening at low temperatures, and not easily volatilizing or coking at high temperatures.
Thermal Stability: After heating at 200℃ for 4 hours, the volatile content is still less than 5%, and the melting temperature is between -47℃ and -31℃.
Low-Temperature Advantage: It can still ensure the normal operation of equipment in extreme environments at -55℃, making it particularly suitable for low-temperature applications in aviation and aerospace.
2. Temperature Resistance Characteristics of Phenyl Silicone Oil
Operating Temperature Range: -70℃ to 300℃ (long-term use -50℃ to 250℃), the solidification point of phenyl silicone oil containing 5 mol% is as low as -70℃, and the flash point is >300℃.
Thermal Stability: The gelation time in 250℃ hot air is 1750 hours, the thermal expansion coefficient is smaller than that of methyl silicone oil, and the thermal loss (250℃/2H) is <2%.
High-Temperature Advantage: High phenyl content (45%+) silicone oil can operate continuously at 300℃ for 5000 hours with a thermal decomposition rate of <0.5%, and with the addition of stabilizers, it can be used for several hundred hours at 300-350℃. 3. Key Differences in Temperature Performance
Low-temperature performance: Low-phenyl silicone oil (5%-10%) maintains fluidity at -70℃, superior to fluorosilicone oil's lower limit of -60℃.
High-temperature performance: High-phenyl silicone oil exhibits better stability in environments above 250℃, making it particularly suitable for applications such as nuclear power plants and high-temperature hydraulic systems.
Temperature stability: Phenyl silicone oil has a higher viscosity-temperature coefficient, meaning its viscosity is less sensitive to temperature changes, resulting in more stable performance under varying temperatures.

III. Comparison of Typical Application Scenarios
1. Advantages of Fluorosilicone Oil
Extreme chemical environments: Fluorine-containing cleaning fluids in semiconductor etching processes, anticorrosive coatings in the chlor-alkali industry, and antifouling coatings for ships.
Low-temperature fuel systems: Aircraft fuel tank sealants, fuel hoses, and oil pressure system seals, especially suitable for environments below -55℃.
Precision machinery lubrication: High-precision bearings in the watch industry, micro-mechanical systems, and laser printer transmission components, reducing friction coefficient by more than 30%.
2. Advantages of Phenyl Silicone Oil
High-temperature electronic equipment: LED packaging materials (refractive index up to 1.52), nuclear power plant seals, and aircraft engine sealing systems.
Extreme temperature environments: Hydraulic systems at Antarctic research stations (cold start time ≤ 3 seconds at -65℃), and sealing materials for deep-sea probes (withstanding pressure of 100 MPa).
High-radiation environments: Radiation-resistant modified models are certified to nuclear power EN standards, extending the maintenance cycle in radiation environments from 3 years to 15 years.
IV. Selection Recommendations
Prioritize fluorosilicone oil: When the application involves strong chemical corrosion environments, fuel systems, or low-temperature (<-60℃) environments, the solvent resistance and chemical stability of fluorosilicone oil make it a more reliable choice, especially suitable for extreme chemical environments in semiconductor, chemical, and aerospace industries.
Prioritize phenyl silicone oil: When the application involves high temperatures (>200℃), high-radiation environments, or electrical insulation, the thermal stability and electrical performance advantages of phenyl silicone oil are significant, making it particularly suitable for nuclear power, LED packaging, and high-temperature hydraulic systems. Hybrid application trend: High-end applications often utilize composite formulations of fluorosilicone oil and phenyl silicone oil, such as fluorinated phenyl silicone oil, to simultaneously achieve comprehensive properties such as high temperature resistance, radiation resistance, and chemical corrosion resistance, meeting the demands of cutting-edge fields such as new energy vehicles and semiconductors.
The selection of these two materials should be based on the specific operating temperature range, media type, and performance requirements. Fluorosilicone oil excels in chemical stability, while phenyl silicone oil is superior in temperature stability.  A rational selection can significantly improve equipment reliability and service life.