How to tell real silicone oil from fake?

　　To distinguish between real and fake silicone oil, you must first familiarize yourself with silicone oil and understand its properties.
　　Silicone oil is a linear polyorganosiloxane with varying degrees of polymerization. It is produced by hydrolyzing dimethyldichlorosilane with water to form initial oligomeric cyclic compounds. These cyclics are then cracked and purified via distillation to yield low-molecular-weight cyclic intermediates. Finally, by combining these cyclics with end-capping agents and a catalyst, a range of mixed products with different degrees of polymerization can be obtained. The silicone oil is subsequently refined through vacuum distillation to remove low-boiling byproducts, resulting in the final product.
　　Silicone oil features include exceptional heat resistance, electrical insulation, weatherability, hydrophobic properties, physiological inertness, and low surface tension. Additionally, it exhibits a low viscosity-temperature coefficient and high compressibility. Some varieties even offer radiation resistance, non-corrosive behavior toward metals, and are completely non-toxic.
　　Silicone oil applications: Commonly used as high-grade lubricants, shock-absorbing oils, insulating oils, defoamers, mold-release agents, polishing compounds, and vacuum diffusion pump oils, among others. Among the various types of silicone oils, methyl silicone oil is the most widely applied and remains a key product in the silicone oil family, followed by methylphenyl silicone oil. Additionally, there are ethyl silicone oil, methylphenyl silicone oil, and nitrile-containing silicone oil, among others. Specialized functional silicone oils and modified silicone oils are primarily designed for specific, niche applications.
　　How to tell real from fake silicone oil:
　　1. Observe with the eyes: Fake silicone oil will appear more cloudy, have a stronger odor, and may even smell unpleasant.
　　2. Testing with Fire: Dip a glass or iron rod into a small amount of silicone oil and ignite it. If it catches fire and produces black smoke, it’s white mineral oil. Pure silicone oil, however, will not burn when ignited—and it’s odorless, crystal-clear, and completely non-toxic. The ignition point of silicone oil is 320°C.
　　3. Freezing Point Test Method: Silicone oil remains unfrozen even at -50°C, whereas counterfeit silicone oil will either become cloudy or freeze altogether.
　　Advantages of silicone oil:
　　1. Excellent shear stability, with the ability to absorb vibrations and prevent their propagation, making it suitable as a damping fluid.
　　2. Excellent thermal oxidation stability, with a thermal decomposition temperature exceeding 300°C, minimal evaporation loss (only 2% after 30 days at 150°C), and negligible changes in viscosity and acid value during an oxidation test conducted at 200°C for 72 hours.
　　3. Excellent electrical insulation properties—volume resistivity remains stable within the temperature range of room temperature to 130°C (however, the oil must be free of water).
　　4. It is a non-toxic oil with low foaming properties and excellent anti-foaming performance, making it suitable for use as a defoamer, among other applications.
　　5. Viscosity-temperature performance is excellent in liquid lubricants, exhibiting minimal viscosity changes across a wide temperature range. Its pour point typically falls below -50°C, with some formulations reaching as low as -70°C. Even during prolonged storage at low temperatures, the oil maintains its original appearance and viscosity—making it an ideal base oil that excels in both high- and low-temperature applications, as well as broader temperature ranges.
　　Drawbacks of silicone oil:
　　1. Low surface tension (easily leaks from the machine).
　　2. The gas has high solubility (making it difficult to design an airtight sealing device).
　　3. Silicone oil has a relatively high coefficient of thermal expansion (which may lead to overpressure issues).
　　4. Silicone oil has poor lubricating properties, especially for steel-on-steel friction pairs.
　　5. Certain hygroscopic properties (electrical performance drops sharply when the water content exceeds 100 × 10⁻⁶).