Mobilgrease 28  

Mobil Grease, Canada

Supreme Performance Greases

Product Description

Mobilgrease 28 is a supreme performance, high temperature, antiwear grease designed to combine the unique features of a polyalphaolefin (PAO) synthetic base fluid with an organo-clay (non-soap) thickener.  The wax-free nature of the synthetic base fluid, together with its low coefficient of traction compared with mineral oils, provide excellent low temperature pumpability, very low starting and running torque, and can reduce operating temperatures in the load zone of rolling element bearings.  The clay thickener provides excellent stability at high temperatures and Mobilgrease 28 has a high dropping point value of 260ºC. . In addition, it resists water washing, provides superior load-carrying ability, reduces frictional drag, and prevents excessive wear. Tests show that Mobilgrease 28 prevents friction oxidation (fretting) and lubricates rolling element bearings under conditions of high speeds and temperatures. It has also shown superior ability to lubricate heavily loaded sliding mechanisms, such as wing flap screwjacks.  Its consistency is between an NLGI No. 1 and No. 2 grease.

Mobilgrease 28 meets the quality level  of U.S. Military Specification MIL-G-81322E, General-Purpose, Aircraft, and is approved against U.S. Military Specification DOD-G-24508A (Navy) for shipboard auxiliary machinery. It can be designated U.S. Military Symbol WTR and NATO Symbol G-395.

Mobilgrease 28 has been the grease of choice for military and related applications, worldwide, for more than 30 years since its introduction. This leading product is based on the synthesized PAO base stocks that were pioneered by the R&D arm of our company resulting in step-out performance not only in grease but in many fluid lubricants, too.

Features & Benefits

Mobilgrease 28 is one of the Mobil brand of PAO-based products recognized and appreciated around the world for innovation and outstanding performance. These molecular design synthetic products, pioneered by our research scientists, symbolize the continuing commitment to using advanced technology to provide outstanding products. A key factor in the development of Mobilgrease 28 is the close contacts between our scientists and application specialists with key OEMs to ensure that our product offerings will provide exceptional performance in the continually evolving aviation equipment designs.

Our work with equipment builders has helped confirm the results from our own laboratory tests showing the exceptional performance of Mobilgrease 28. A particular need of aviation greases is the need to resist high temperature stresses, while providing excellent starting and low torque at low-temperature.To meet this combination of needs our product formulation scientists chose proprietary synthetic base oils for Mobilgrease 28 because of their exeptional thermal/oxidative resistance potential, and superb low-temperature capability. Our formulators chose specific thickener chemistry and a prorietary additive combination which would maximize the benefits of the synthetic base oils.

Mobilgrease 28 meets the requirements of key military and commercial aviation specifications and has built up a superb reputation for performance and reliability among users around the world. Mobilgrease 28 provides the following advantages and potential benefits:

Features Advantages and Potential Benefits
High viscosity index base stock with no wax content Very wide operating temperature range - outstanding high and low temperature performance
Excellent film protection at high temperatures
Minimum resistance to start-up at extremely low temperatures
Low traction base oil Low sliding friction and reduced heat build-up
Potential for energy savings
Excellent protection against fretting wear and corrosion Superb bearing protection and extended bearing life and reduced bearing replacement costs
Extreme-pressure characteristics Avoids excessive wear, even under shock load
High thermal/oxidative stability Extended relubrication intervals
High resistance to water washout Maintains excellent grease performance in adverse weather and other water-exposure conditions
Compatible with mineral-oil-base greases Avoids complex conversion procedures from mineral products, though complete replacement needed to assure full benefits


Mobilgrease 28 is designed for the lubrication of plain and rolling bearings at low to high speeds, and splines, screws, worm gears, and other mechanisms where high friction reduction, low wear, and low lubricant friction losses are required. The recommended operating temperature range is -55º to 180ºC with appropriate relubrication intervals.

Mobilgrease 28 meets the quality level of military specifications MIL-G-81322D for wide temperature range aviation service and approved under DOD-G-24508A for shipboard service.  Specific military and civil aviation applications include:
-Landing wheel assemblies
-Control systems, screwjacks, servo devices, actuators, sealed-bearing motors and oscillating bearings
-Helicopter rotor bearings on aircraft and on naval shipboard auxiliary machinery
-It also can be used where superseded specifications MIL-G-81322 (WP), MIL-G-7711A, MIL-G-3545B, and MIL-G-25760A may be called for

Mobilgrease 28 also is recommended for industrial lubrication, including sealed or repackable ball and roller bearings wherever extreme temperature conditions, high speeds, or water washing resistance are factors. Typical industrial applications include:
-Conveyor bearings
-Small alternator bearings operating at temperatures near 177ºC
-High-speed miniature ball bearings, and bearing situations where oscillatory motion, vibration, and fretting create problems.

Specifications & Approvals

Meets the following industry and builder specification: Mobilgrease 28
Quality Level USDA H-2X

Has the following builder approvals Mobilgrease 28
DOD-G-24508 A Amendment 1X

Also recommended for use in applications requiring Mobilgrease 28

Military Mobilgrease 28
Approved against Mil-G-81322E quality levelX

Typical Properties

Mobilgrease 28
NLGI Grade1.5
Thickener Type Clay
Color, VisualRed
Penetration, Worked, 25ºC, ASTM D 217 280
Dropping Point, ºC, ASTM D 2265310
Viscosity of Oil, ASTM D 445 
cSt @ 40ºC29.3
Low Temp. Torque at -54ºC 
Starting, g-cm10000
Running, g-cm1000
Penetration, Worked, FTM 313, X100,000, 1/16" holes, mm/10320
Oil Separation, 30 hr. at 177ºC, ASTM D 6184, vol-%2.5
Evaporation Loss, ASTM D 2595, 22 hrs @ 177ºC, vol-%5.2
Copper Strip Corrosi0n, ASTM D 130, 24 hrs @ 100ºC1B
4 Ball Wear, ASTM D 2266, Scar,mm0.5
Load Carrying Capacity, ASTM D 2596, Load Wear Index, kgf44

Health & Safety

Based on available information, this product is not expected to produce adverse effects on health when used for the intended application and the recommendations provided in the Material Safety Data Sheet (MSDS) are followed.  MSDS's are available upon request through your sales contract office, or via the Internet.  This product should not be used for purposes other than its intended use.  If disposing of used product, take care to protect the environment.

The Mobil logotype, the Pegasus design and Mobilgrease are trademarks of ExxonMobil Corporation, or one of its subsidiaries.


Imperial Oil

Petroleum and Chemicals Division
Lubricants and Specialties
240 Fourth Ave SW
C. P. 2480, Station M
Calgary AB T2P 3 M 9


Typical Properties are typical of those obtained with normal production tolerance and do not constitute a specification. Variations that do not affect product performance are to be expected during normal manufacture and at different blending locations. The information contained herein is subject to change without notice. All products may not be available locally. For more information, contact your local ExxonMobil contact or visit
ExxonMobil is comprised of numerous affiliates and subsidiaries, many with names that include Esso, Mobil, or ExxonMobil. Nothing in this document is intended to override or supersede the corporate separateness of local entities. Responsibility for local action and accountability remains with the local ExxonMobil-affiliate entities.