Dimethyl silicone oil 201 series PDMS viscosity guide MOON Tech Anhui
📖 Silicone Oil Selection Guide  |  CAS 63148-62-9  |  Viscosity 5–100,000 cSt

What Is Silicone Oil?

Silicone oil is a polymer based on polydimethylsiloxane (PDMS) — a backbone of alternating silicon and oxygen atoms with two methyl groups attached to each silicon. This Si–O–Si structure gives silicone oils their characteristic properties: low surface tension, high thermal stability, excellent dielectric properties, and wide operating temperature range.

Unlike mineral oils, silicone oils are chemically inert and do not carbonize easily at high temperatures. They are supplied in a wide range of viscosities from water-thin (0.65 cSt) to extremely viscous (over 1,000,000 cSt), and in several chemical types suited to different performance requirements.

Viscosity: The Primary Selection Parameter

Viscosity is measured in centistokes (cSt) and determines almost everything about how the oil behaves in your process. The table below is a practical starting reference — use it to narrow your options before matching to a chemical type.

Viscosity Range Typical Feel / Behaviour Common Applications
0.65 – 10 cStWater-thin, highly mobileAnti-foam agents, release agents, cosmetics (quick absorb)
10 – 100 cStLight, pourableTextile lubricants, cosmetic base oils, defoamers
100 – 1,000 cStMedium body, free-flowingGeneral industrial lubrication, cosmetics, dust control
1,000 – 10,000 cStModerately viscous, slow-flowingHydraulic fluids, mold release, fiber lubricants
10,000 – 100,000 cStThick, viscousHigh-temperature lubrication, sealants, polymer additives
100,000 – 1,000,000 cStVery thick, paste-likeGrease compounding, rubber modification, thermal interface materials

When you are uncertain of the right viscosity for your process, the most practical approach is to describe your application — process temperature, substrate, method of application and performance requirement — and let us recommend a grade. We maintain viscosity tolerances of ±5% on standard grades.

Types of Silicone Oil: A Quick Comparison

Five chemical types cover the majority of industrial and cosmetic applications. Each offers a distinct performance profile.

🔵 Dimethyl Silicone Oil (201 Series)

The workhorse type. Inert, thermally stable (-40 to 200°C), electrically insulating. Standard for industrial lubrication, release, defoaming and thermal transfer.

1 – 1,000,000 cSt

🔘 D5 Cyclic Siloxane

Volatile cyclic siloxane (evaporates at room temperature). Light texture, excellent spreadability. Widely used in cosmetics and as RTV-2 release agents.

4 – 6 cSt (volatile)

🟣 Methyl Phenyl Silicone Oil

Phenyl-modified PDMS. Retains fluidity and stability at temperatures where standard PDMS degrades. Higher refractive index. For high-temp and radiation applications.

10 – 800 cSt

⚡ Hydrogen-Containing Silicone Oil

Contains Si–H bonds. Reacts with alkenes and hydroxyl groups to form cured films. Used in waterproofing textiles, personal care conditioning, and addition-cure formulations.

5 – 300 cSt

💜 Vinyl Silicone Oil

Contains vinyl groups (-CH=CH₂) at chain ends or side chains. Essential raw material for addition-cure (platinum-catalysed) silicone rubber — LSR, HTV and RTV-2 systems.

100 – 100,000 cSt

Selection by Application

Once you have narrowed the viscosity range, the chemical type is determined by the application environment. Here are the most common use cases and the type we typically recommend.

🏭 General Industrial Lubrication

Use dimethyl silicone oil (201 series), viscosity 50–1,000 cSt depending on the mechanism. Low friction, wide temperature range, chemically inert toward most metals and polymers.

Dimethyl silicone oil 201-350cst lubricating plastic gear assembly industrial machinery
Dimethyl silicone oil 201-350cst — low-viscosity PDMS for plastic and rubber component lubrication (bearings, seals, chains)

🧴 Cosmetics & Personal Care

Choose D5 for light, quick-drying textures in serums and deodorants. Low-viscosity dimethicone for smooth skin feel in lotions. Dimethiconol in D5 for durable film-forming in hair conditioners.

Dimethyl silicone oil 201-1000cst personal care cosmetics hair serum skin care lotion formulation
201-1000cst PDMS — silky, non-greasy spreadability in hair serums, lotions and color cosmetics

🧵 Textile Finishing

Hydrogen-containing silicone oil for durable softness and hydrophobicity on fabrics. Dimethyl oil for fiber lubricants in spinning and weaving. Dosage typically 0.5–5 g/L bath.

🏗️ Mold Release

D5 or low-viscosity dimethyl silicone oil (5–50 cSt) applied as a thin film before casting. D5 evaporates after use, leaving a clean part. Non-evaporating grades for reusable moulds.

🔥 High-Temperature Lubrication

Methyl phenyl silicone oil retains viscosity and does not coke at 250–300°C where standard dimethyl oil degrades. For oven chains, conveyor belts and thermal oil systems.

Dimethyl silicone oil heat transfer fluid industrial thermal management closed-loop system
201-1000cst silicone oil in industrial heat transfer system — thermally stable to 200°C, zero corrosion

💧 Waterproofing & Surface Treatment

Hydrogen-containing silicone oil reacts with -OH groups on mineral surfaces (stone, concrete, glass) to form a durable hydrophobic film. Applied diluted in solvent or emulsion.

Damping hydraulic silicone oil 201-350cst precision instrument shock absorber
201-350cst silicone damping fluid — consistent viscosity -50°C to 150°C, zero noise, no maintenance

💡 LED & Optical Encapsulation

201-1000cst dimethyl silicone oil offers a refractive index of 1.403 — very close to glass — making it ideal for LED dome encapsulation, optical lens bonding, and fiber optic couplers. It transmits light with minimal reflection loss, remains thermally stable at high temperatures, and protects LED chips from moisture and dust ingress.

LED optical encapsulation silicone oil lens bonding refractive index 1.403 fiber optic coupler
201-1000cst silicone oil — RI 1.403 reduces interfacial light reflection in LED lens bonding and optical couplers

☀️ Solar PV & Thermal Management

201-1000cst silicone oil is used in solar PV inverter heat exchange systems, concentrated solar power (CSP) thermal storage, and lab precision heating baths. Its high specific heat capacity, wide operating range (-40°C to 200°C), and chemical inertness make it the clean, reliable alternative to mineral-based thermal fluids.

Solar PV inverter thermal management silicone oil heat exchange photovoltaic cooling system
201-1000cst thermal management silicone oil in solar PV inverter cooling — -40°C to 200°C operating range

⚡ Transformer & Electrical Insulation

201-350cst silicone dielectric oil is a fire-safe alternative to mineral oil in power transformers. Dielectric strength exceeds 15 kV/mm, flash point is above 300°C — significantly reducing fire risk in indoor and rooftop transformer installations. Its hydrophobic surface prevents moisture ingress, extending transformer service life.

Transformer dielectric insulating oil silicone oil 201-350cst power distribution switchgear high voltage
201-350cst silicone dielectric oil — dielectric strength > 15 kV/mm, flash point > 300°C, fire-safe transformer insulation

What Moon Technology Supplies

We manufacture and supply the full range of silicone oil types from our facility in Bengbu, Anhui. All grades are available with TDS, MSDS and batch COA. Sample quantities of 1–2 kg are available for quality evaluation.

Product Type Viscosity Range Key Certifications
201 Dimethyl Silicone OilDimethyl / PDMS5 – 100,000 cStFDA 21 CFR 173.340, Kosher
D5 CyclopentasiloxaneCyclic (D5)4 cSt (volatile)REACH, FDA, EU Cosmetics Regulation
Methyl Phenyl Silicone OilPhenyl-modified10 – 800 cStIndustrial grade
Hydroxy Silicone Oil (107)Hydroxy-terminated PDMS1,000 – 70,000 cStIndustrial grade
Vinyl Silicone OilVinyl-functional100 – 100,000 cStLSR / HTV grade

Not Sure Which Grade Fits Your Process?

Describe your application — temperature range, substrate, method of use and performance target. We will recommend a grade and send a sample for your trials.

📩 Ask Our Technical Team

Frequently Asked Questions

Q: What is the difference between dimethyl silicone oil and functional silicone oils?
Dimethyl silicone oil (PDMS) is the most widely used type — inert, thermally stable, and suitable for general lubrication, release and defoaming. Functional variants carry reactive groups: phenyl for high-temperature and radiation resistance; hydrogen-containing for waterproofing and cure reactions; vinyl for addition-cure rubber and further modification; hydroxy for condensation-cure systems. Choosing the right type depends on whether the oil needs to react with other materials or simply provide a stable lubricating film.
Q: How do I choose the right viscosity for my application?
Viscosity is the single most important selection parameter. General rules: 5–50 cSt for sprayable or thin-film applications (anti-foam, release agents); 100–1,000 cSt for manual lubrication, cosmetics and textile finishing; 1,000–10,000 cSt for hydraulic fluids, mold release and general industrial use; 10,000–100,000 cSt for high-viscosity lubrication, sealants and polymer modification; 100,000+ cSt for thick greases and rubber compounding. When in doubt, share your process conditions and we will recommend a starting viscosity.
Q: What is the difference between D5, D6 and dimethyl silicone oil?
D5 (cyclopentasiloxane, CAS 541-02-6) and D6 (cyclomethicone, CAS 540-97-6) are cyclic siloxanes — small ring-structured molecules that evaporate readily at room temperature. They are widely used in cosmetics for their light texture and quick-drying feel. Linear dimethyl silicone oil (201 series) is a chain-structured PDMS that does not evaporate and is the standard choice for industrial lubrication, hydraulic fluids and thermal transfer applications. The key distinction is volatility: cyclic types evaporate, linear types persist.
Q: Can silicone oil be used in high-temperature environments?
Standard dimethyl silicone oil begins to gel above 250°C. For high-temperature applications (200–300°C continuous), use phenyl-modified silicone oil, which retains its properties through thermal-oxidative environments. For extreme temperatures above 300°C or where radiation resistance is needed, fluorosilicone oil or specialized high-phenyl fluids are appropriate. For cryogenic applications below -40°C, low-phenyl silicone oil maintains fluidity where standard PDMS becomes waxy.
Q: Which silicone oil is best for cosmetics and personal care?
The most common choices for cosmetics are D5 (cyclopentasiloxane) for light, quick-drying textures in antiperspirants and serums; low-viscosity dimethyl silicone oil (2–10 cSt) for silky skin feel in lotions and creams; and high-viscosity dimethiconol in D5 blends for durable film-forming in conditioners and hair serums. Methyl phenyl silicone oil provides a unique velvety sensation and higher refractive index for premium skin-care and lip products. All should comply with the relevant FDA or EU cosmetic regulations for the target market.
Q: What are the typical MOQ and lead time for silicone oils?
MOQ is typically 200 kg for standard grades in drums, with bulk pricing available from 800 kg upwards. Lead time is 7–15 days for in-stock grades. Custom viscosity or special grades may require 15–25 days. Free samples of 1–2 kg are available for quality evaluation; TDS and MSDS are supplied with every batch.

Ready to Specify a Silicone Oil for Your Application?

Tell us the viscosity you need, the application, and the temperature range — we will confirm the grade, send the TDS and arrange a sample shipment within 24 hours.

📩 Request TDS & Sample