81MS Greases by Royco

Royco 81MS is a high-temperature, molybdenum disulfide (MoS₂)-fortified aircraft grease designed for extreme-pressure and severe-duty applications. It is formulated to lubricate low-speed sliding metal-on-metal surfaces exposed to high heat and heavy loads. In addition to lubrication, it also functions as an anti-seize compound for threaded assemblies. Royco 81MS is widely used in aviation maintenance where thermal stability and load protection are critical.

Royco 81MS is commonly used on low-speed sliding metal surfaces in aircraft gas turbine engines and other high-temperature areas. It is also applied to threaded fasteners as an anti-seize compound to prevent galling and seizure. Typical applications include steel surface protection, spline lubrication, and sliding mechanisms exposed to severe heat. Always consult the aircraft maintenance manual for approved uses.

Molybdenum disulfide acts as a solid lubricant, reducing friction under extreme pressure and temperature conditions. In Royco 81MS, MoS₂ particles bond to metal surfaces, forming a durable lubricating film. This film continues to provide protection even if the oil component evaporates under high heat. The result is reduced wear, improved anti-seize performance, and enhanced component longevity.

Royco 81MS is formulated with a silicone-based oil and micro-fine molybdenum disulfide for exceptional thermal stability. It provides effective lubrication at operating temperatures up to approximately 750°F (400°C) and anti-seize protection at temperatures up to 1,400°F (760°C). Its oxidative resistance helps prevent breakdown under prolonged exposure to heat. These characteristics make it ideal for aerospace environments where extreme temperatures are present.

Royco 81MS meets the requirements of MIL-DTL-25681 and carries the NATO symbol S-1735. These specifications confirm compliance with military and aerospace performance standards. Meeting these requirements ensures the grease performs reliably in approved aviation applications. Always verify current specification references in the applicable maintenance documentation.

Royco 81MS prevents metal-to-metal adhesion in threaded fastener applications and high-temperature assemblies. The molybdenum disulfide film reduces friction and prevents galling during installation and removal. This helps protect threads from damage and simplifies future maintenance. Anti-seize protection is especially valuable in turbine engine components and exhaust system hardware.

Royco 81MS helps protect critical aircraft components exposed to extreme heat and pressure. By reducing friction and preventing seizure, it minimizes the risk of component damage during operation and disassembly. Reliable high-temperature lubrication supports system durability and maintenance efficiency. Proper grease selection is essential for maintaining airworthiness and regulatory compliance.

Royco 81MS is designed for extreme-pressure environments where metal contact occurs under load. The MoS₂ additive provides a protective barrier that prevents surface scoring and wear. This makes it suitable for slow-moving or static components under significant mechanical stress. Its load-carrying capability helps extend component service life.

Yes, Royco 81MS may also be used in industrial or marine environments requiring high-temperature lubrication and anti-seize protection. Applications involving heavy equipment, high-heat fasteners, or sliding metal assemblies may benefit from its performance characteristics. However, compatibility with specific systems should be verified before use. In aviation, usage must always align with approved maintenance documentation.

Royco 81MS should be applied to clean, dry surfaces in accordance with the aircraft manufacturer’s lubrication instructions. Excess grease should be avoided to prevent contamination of adjacent components. Proper storage in a cool, dry location helps maintain product integrity. Following approved application procedures ensures optimal performance and safety.

Unlike general-purpose aviation greases, Royco 81MS is specifically formulated for extreme-temperature and anti-seize applications. Its high molybdenum disulfide content and silicone-based oil system provide superior thermal resistance. This makes it particularly suitable for turbine engine and exhaust system components. Selecting the correct grease depends on load, temperature, and application requirements.