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Mobilgrease 28

Synthetic Aviation Grease

Product Description

Mobilgrease 28 is a supreme performance, wide-temperature, antiwear grease designed to combine the unique features of a polyalphaolefin (PAO) synthetic base fluid with an organo-clay (non-soap) thickener. Its consistency is between an NLGI No. 1 and No. 2 grease. It offers outstanding performance over a wide temperature range. The wax-free nature of the synthetic base fluid, together with its high viscosity index compared to mineral oils, provide excellent low temperature pumpability, very low starting and running torque, and can help reduce operating temperatures in the load zone of rolling element bearings.

The clay thickener gives Mobilgrease 28 a high dropping point value of around 300ºC, which provides excellent stability at high temperatures. Mobilgrease 28 resists water washing, provides superior load-carrying ability, reduces frictional drag, and prevents excessive wear. Tests show that Mobilgrease 28 lubricates effectively rolling element bearings under conditions of high speeds and temperatures. Mobilgrease 28 has also shown excellent ability to lubricate heavily loaded sliding mechanisms, such as wing flap screw jacks.

For more than 30 years, Mobilgrease 28 has been the multi-purpose grease of choice for military and related aviation applications, worldwide.

 

Features and Benefits

A particular requirement 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 ExxonMobil product formulation scientists chose synthetic hydrocarbon base oils for Mobilgrease 28 because of their low volatility, exceptional thermal/oxidative resistance, and superb low-temperature capability. Formulators chose specific thickener chemistry and a proprietary additive combination which helps 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:

FeaturesAdvantages and Potential Benefits
High viscosity index (VI) synthetic base stock with no wax contentAllows wide operating temperature range - outstanding high and low temperature performance
 Provides thicker fluid films protecting against wear of equipment parts operating at high temperature
 Causes low resistance during start-up at very low temperatures
Excellent protection against wear and corrosionSuperb bearing protection and helps extend bearing life and reduce bearing replacement costs
Extreme-pressure protection characteristicsAvoids excessive wear, even under shock load
High thermal/oxidative stabilityLong relubrication intervals
High resistance to water washoutMaintains excellent grease performance in adverse weather and other water-exposure conditions

 

Applications

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 -54ºC to 177ºC (-65ºF to 350ºF) with appropriate relubrication intervals.

Mobilgrease 28 is recommended for use in landing wheel assemblies, control systems and actuators, screw jacks, servo devices, sealed-bearing motors, oscillating bearings, and helicopter rotor bearings on military and civil aircraft. Subject to equipment manufacturer approvals, it can also be used on naval shipboard auxiliary machinery and where superseded specifications MIL-G-81322 (WP), MIL-G-7711A, MIL-G-3545B, and MIL-G-25760A are recommended.

Mobilgrease 28 is also 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 (350ºF), high-speed miniature ball bearings, and bearing applications where oscillatory motion, and vibration create problems.

Mobilgrease 28 is qualified by the U.S. Military under Specification MIL-PRF-81322, General-Purpose, Aircraft, and Specification DOD-G-24508A (Navy) for shipboard auxiliary machinery. It is a U.S. Military Symbol WTR and NATO Code Number G-395 grease.

 

Specifications and Approvals

 

Mobilgrease 28Is Approved AgainstQuality Level
MIL-PRF-81322G               X  
DOD-G-24508A, Amendment 4          X 
NATO G-395               X 

 

 

Typical Properties

 Test MethodsMobilgrease 28 Typicals (1)MIL-PRF-81322 Limits
NLGI Grade 1 1/2 
Thickener Type Clay (non-soap) 
ColorVisualDark Red 
StructureVisualSmooth, buttery 
Dropping Point, ºC (ºF)ASTM D 2265307 (584)232 (450) min
Viscosity of Base Oil, cStASTM D 445  
at 40ºC 30 
at 100ºC 5.7 
Low Temp. Torque at -54ºC (-65ºF), Nm (g-cm)ASTM D 1478  
Starting 0.43(4400)0.98 (10,000) max
Running, after 1 Hr 0.05 (510)0.098 (1,000) max
Penetration @ 25ºC (77ºF), 60 Stoke Worked, mm/10ASTM D 217293265-320
Extended Worked Penetration Stability, 100,000 Strokes, mm/10FTM 313303350 max
Oil Separation, 30 Hrs at 177ºC, wt %ASTM D 61843.52.0 - 8.0
Evaporation Loss, 22 Hrs at 177ºC, wt %ASTM D 2595610 max
Copper Strip Corrosion, 24 Hrs at 100ºCASTM D 40481b1b max
Four-Ball Wear, Scar dia, mmASTM D 22660.60.8 max
Load Wear Index, kgfASTM D 25964030 min
Rust Protection, 48 Hrs at 125ºF, › 1mm dia Corrosion SpotsASTM D 1743Pass0
Water Washout, 1 Hr at 41ºC, wt %ASTM D 1264120 max
High Temperature Performance, Hrs at 177ºCASTM D 3336 (modified)Pass400 min
Oxidation Stability, pressure drop in kPaASTM D 942  
100 Hrs at 99ºC Pass83 max
500 Hrs at 99ºC Pass172 max
Dirt Count, Particles/mLFTM 3005  
25-74 Micron Pass1000 max
75 Micron or Larger 00
Oscillation Friction and Wear, Scar Dia, 35,000 cycles, 90º Angle, Aluminum Bronze Block, mmModified ASTM D 3704Pass6.35 max
Rubber Swell, L Type Synthetic, 1 week at 70ºC (158ºF), vol %FTM 3603610 max
(1) Typical properties are typical of those obtained with normal production tolerance and may vary slightly, while remaining within specified limits.   

 

Health and Safety

Based on available toxicological information, this product is not expected to produce adverse effects on health when used and handled properly. Information on use and handling, as well as health and safety information, can be found in the Material Safety Data Sheet (MSDS) which can be obtained from your local distributor or via the Internet on http://www.exxonmobil.com/lubes.

PDS AV-05


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

4-2013 

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