MOLYKOTE 55
Harmonization Code : 3403.19 | Lubricating Preparations (With 70% or More Petroleum Oils) For Automotive and Other Uses
Main features
- Silicone Base Oil and Lithium Soap Thickener
- Heat-Stable Oxidation-Resistant Grease
- D4/D5/D6 Cyclic-Siloxane Compliance
Product Description
MOLYKOTE® 55 O-Ring (S) Grease is a beige silicone-based grease formulated with silicone oil, ester oil, and lithium soap for lubricating rubber-to-metal O-ring and seal interfaces in pneumatic systems. The documented service range is -65°C to +175°C, with ASTM D1478-80 low-temperature torque data measured at -65°C. Typical retention data include less than 1% evaporation and less than 7% bleed after 24 hours at 150°C, plus 3% oil separation after 7 days at 40°C. The formulation is designed to slightly swell compatible rubber O-rings and seals while supporting lubrication and sealing. For ultra-low cyclic silicone lubricant programs, it complies with the limits on cyclic siloxanes (D4, D5 and D6) in accordance with Regulation (EU) 2024/1328. Material response can vary with elastomer formulation and plasticizer content, so small-scale compatibility testing should be conducted before use in a specific assembly.
Key features
- Wide service-temperature range: Documented for approximately -65°C to +175°C service.
- Low-temperature torque data: 115 × 10-3 N·m initial breakaway torque and 21 × 10-3 N·m after 20 minutes at -65°C.
- Condition-specific evaporation data: Less than 1% evaporation after 24 hours at 150°C; this is a measured retention result, not a universal outgassing or low-fogging qualification.
- Ultra-low cyclic regulatory positioning: Complies with the limits on cyclic siloxanes D4, D5 and D6 in accordance with Regulation (EU) 2024/1328.
- Water and corrosion test data: Static water-resistance rating 0-90 at 90°C for 3 hours, 5.2% ASTM D1264 water washout, and SKF-EMCOR corrosion degree 0.
- Application flexibility: Apply by brush, grease gun, automatic lubrication equipment, or centralized lubrication system; do not mix with other greases.
- Compatibility control: Intended for elastomer-containing interfaces, with small-scale material compatibility testing required for the exact seal or polymer grade.
Applications / Suitable for
- Rubber-to-metal O-rings and seals in pneumatic systems
- Aircraft pneumatic-system O-ring and seal lubrication
- Automotive pneumatic-system O-ring and seal lubrication
- General industrial pneumatic-system O-ring and seal lubrication
TDS, SDS & Technical Documents
Technical Specifications
No specifications available.
Additional Information
MOLYKOTE® 55 O-Ring (S) Grease
A beige silicone-based grease using silicone oil, ester oil, and lithium soap for rubber-to-metal O-ring and seal interfaces in aircraft, automotive, and general industrial pneumatic systems. It provides a -65°C to +175°C service range, low-temperature torque and retention data, and controlled material-compatibility guidance. For ultra-low cyclic silicone lubricant programs, it complies with the limits on cyclic siloxanes D4, D5 and D6 in accordance with Regulation (EU) 2024/1328.
MOLYKOTE® 55 O-Ring (S) Grease is a beige silicone-based grease for O-ring and seal lubrication.
Grease composition, consistency, and physical properties
| Property | Value | Unit | Method / condition |
|---|---|---|---|
| Color | Beige | — | As supplied |
| Kinematic base-oil viscosity | 100 | mm²/s | DIN 51562; 25°C |
| Worked penetration | 260–300 | mm/10 | ISO 2137 |
| Density | 0.98 | g/cm³ | ISO 2811; 25°C |
| Dropping point | ≥195 | °C | ASTM D2265; test transition, not the service-temperature limit |
Supplier data are identified as preliminary and typical; they are not specification limits. Base-oil viscosity, penetration, and dropping point describe different properties and should not be treated as interchangeable service limits.
Temperature, retention, and in-service test results
The results below are condition-specific evaluation data. Evaporation, bleed, oil separation, oxidation, friction, water resistance, washout, and corrosion are different measurements; none should be converted into a universal low-outgassing, contamination-free, maintenance-life, or system-reliability claim.
| Property | Value | Unit | Method / condition |
|---|---|---|---|
| Service temperature | -65 to +175 | °C | Approximate product service range |
| Initial breakaway torque | 115 × 10-3 | N·m | ASTM D1478-80; -65°C |
| Torque after 20 min | 21 × 10-3 | N·m | ASTM D1478-80; -65°C, after 20 min |
| Bleed | <7 | % | ASTM D6184; 150°C / 24 h |
| Evaporation | <1 | % | ASTM D6184; 150°C / 24 h |
| Oil separation | 3 | % | DIN 51817; 40°C / 7 days |
| Oxidation pressure loss | ≤100 | mbar | DIN 51808; 100 h at 99°C |
| RapidOxy 100 oxidation stability | 900 | min | DIN 51830-1; accelerated procedure at 160°C |
| Coefficient of friction | 0.02 | µ | Steel ball / POM; 12.7 mm ball, 6.3 N, 10 mm/s, 24 h |
| Static water resistance | 0-90 | rating | DIN 51807 part 1; 90°C / 3 h |
| Water washout | 5.2 | % | ASTM D1264 |
| Corrosion degree | 0 | rating | DIN 51802; SKF-EMCOR method |
Use the evaporation result as the measured ASTM D6184 value at 150°C for 24 hours. It does not establish low-fogging, low-outgassing, vacuum suitability, lubricant-migration limits, or sensor/optics compatibility without application-specific evidence.
Apply to a verified O-ring or seal material and avoid lubricant mixing
The grease may be applied by brush, grease gun, automatic lubrication equipment, or centralized lubrication systems. Because the formulation is intended to interact with elastomer seals, material compatibility is a selection step rather than an assumed property of every rubber or plastic grade.
Use the final processing visual to show controlled O-ring or seal lubrication at a rubber-to-metal pneumatic interface.
Store between 0°C and 40°C in the original unopened container. Usable life is 60 months from the date of production. Review the current safety information and container label before handling. Do not use with liquid oxygen or other strong oxidizers.
O-ring and pneumatic-system applications
The documented application scope is lubrication between rubber and metal parts in pneumatic systems. For other contamination-sensitive assemblies, qualify the exact interface, material pair, operating conditions, and cleanliness requirement before treating the grease as a suitable solution.
Evaluate MOLYKOTE® 55 O-Ring (S) Grease for your seal interface
Krayden can help review the O-ring or seal material, mating surface, pneumatic duty, temperature range, lubricant quantity, application method, cyclic-siloxane limits, and contamination-control requirements. For ultra-low cyclic programs or applications involving sensors, optics, or electronics, qualify any low-fogging, outgassing, migration, and assembly-cleanliness targets separately.
