Krytox™ MIL PRF-27617 Greases—Grease, Aircraft and Instrument, Fuel- and Oxidizer-Resistant

MIL PRF-27617 Greases

Product Information

Krytox™ oils and MIL PRF-27617 greases are based on perfluoropolyether (PFPE) oils. These synthetic fluorinated lubricants are used in extreme conditions, such as continuous high temperatures up to 300 °C (572 °F) and higher temperatures for shorter periods, depending on product grade limits. Chemically inert and safe for use around hazardous chemicals, these lubricants are nonflammable and are safe for use in oxygen service. Krytox™ oils and greases are silicone free and do not damage plastics or elastomers, or cause corrosion to metals. They are commonly used as lubricants in aerospace, automotive, industrial, and semiconductor applications, as well as solving many other routine lubrication problems.

Krytox™ greases are the original products that this military specification was written for and have been certified continuously since the specification was originally written.

This is the latest data from the recertification that is required every five years. Krytox™ greases are standard as NLGI Grade 2 penetration. If the 240 AZ is ordered to meet MIL-SPEC requirements, it must be ordered as NLGI Grade 1 to meet the specification.

Typical Applications

Applications for Krytox™ lubricants are generally of a critical nature with temperatures in all industries reaching extremes for conventional lubricants. They are expected to be durable in the most aggressive environments and are now often considered an integral part of the design. Where failure of components is not an option, whether because of durability, warranty, safety, loss of productivity, or down time, Krytox™ is the lubricant of choice in a wide range of industries and applications.

In the aerospace industry, Krytox™ oils and greases are applied on various settings, spanning from bearings and sealants to O-rings and oxygen systems. Krytox™ is a valuable asset to the aerospace industry, due to its superior performance in a wide range of temperatures scaling from 70 to 399 ºC (–100 to 750 ºF). In addition, it is robust in harsh environments and has excellent frictional properties, allowing it to resist change in properties over time, provide longer wear, and lower energy consumption. Krytox™ lubricants are compatible with all metals, elastomers, plastics, paints, and finishes. Due to the intense and severe circumstance of the
aerospace industry, it can be expected that Krytox™ delivers a high level of product excellence.

Krytox™  240 AC, 240 AB, and 240 AZ gr-1 are MIL PRF-27617 greases and now have NSF approval for incidental food contact (H-1) in and around food processing areas.

Preparation Before Packing Bearings With Grease

New bearings and equipment that are not lubricated often have rust preventive oils in them to prevent damage while they are in storage before use. New bearings should be inspected for damage and cleanliness before use. The greases or preservative oils need to be removed when using Krytox™ as a lubricant. Failure to do so could result in reduced bearing life. Bearing life tests on uncleaned bearings have shown reduced life in high temperature, high speed tests, where the bearing was filled with a minimum amount of grease. The preservatives coat the metal surface to prevent rusting, so they can also prevent the grease from adhering, causing them to be thrown off by the action of the bearing. They also will oxidize and harden, and can create debris that will contaminate the grease.

Storage and Shelf Life

Krytox™ grease and oil lubricants have an indefinite shelf life, if unopened and stored in a clean dry location.

CAGE No.: 43S57

SIC Code: 2992 Lubricating Oils and Greases

NAICS Code: 324191 Lubricating Oils and Greases Manufacturing

DUNS: 557214574

Krytox™ MIL PRF-27617 Greases240 AZ240 AB240 AC
Qualification Reference Number, 1 Oct 2008AFPET/PTPT 08-011AFPET/PTPT 08-012AFPET/PTPT 08-013
Grease Type/Operating Range, °C (°F)Type I/–54 to 149
(–65 to 300)
Type II/–40 to 204
(–40 to 399)
Type III/–34 to 288
(–29 to 550)
NATO NumberG-397G-398G-399
Penetration GradeNLGI 1NLGI 2NLGI 2
Change in Worked Penetration (30 max.)133–3
Corrosion on Copper (2b max.)1b1b1b
High Temperature Bearing Performance
(500 hr min. at 10,000 RPM, 204 °C [399 °F])
Stopped at 1,320 hrStopped at 1,685 hr
Evaporation ASTM D-2595, %12.910.10.2
Oil Separation, %14.215.5
Solubility in Fuel (20% max.), %0.30.1
Liquid Oxygen Impact Sensitivity
20 impacts at 43.3 in, no reaction
No ReactionNo ReactionNo Reaction
Water Washout Characteristics (20% max.), %0.25
Oxidation Stability (5 max.), psi0.5
Dirt Count
75 μ and larger (0 per cc max.)
25 to 74 μ (1000 per cc max.)
Resistance to Aqueous Solution
Distilled Water
50/50 Distilled Water/Ethanol


Film Stability and Corrosion on SteelPassPassPass
Krytox™ Base Oil Viscosity, 40 °C (104 °F), cSt22.877.8243
Krytox™ Useful Range, °C–57 to 149–40 to 232–34 to 288

If these greases are not right for you, please click here to learn more about Krytox greases and oils.

Krytox™ is  a trademark of The Chemours Company FC, LLC.

The recommendation made here with and the information set forth with respect to the performance or use of our products are believed, but not warranted to be accurate. The products discussed are sold without warranty, as to fitness or performance, express or implied and upon condition that purchasers shall make their own test to determine suitability of such products for their particular purposes. Likewise, statements concerning the possible uses of our products are not intended as recommendations to use our products in the infringement of any patent.