Mobil Arapen RB 320  

Mobil Grease, United States

View  Arapen RB 320


Product Description

Mobil Arapen RB 320 is a high performance long-life grease developed for the roller bearings of railroad car journals where no provision is provided for in-service re-lubrication. It is formulated with a mineral base fluid and a mixed lithium / calcium soap thickener. Mobil Arapen RB 320 grease has the high oxidation stability required to maintain good lubrication throughout extended periods of service or storage. It is highly resistant to chemical deterioration that might otherwise produce acids or deposits that are detrimental to long bearing life. Mobil Arapen RB 320 grease has exceptional ability to withstand shear, i.e. retain consistency after prolonged working, as in the churning action of an anti-friction bearing. This grease has been shown to have little effect on seal materials. Largely because of its special calcium-lithium-soap base, Mobil Arapen RB 320 grease has a high resistance to structural change in the presence of water. It is also inhibited to give protection against rusting.

Mobil Arapen RB 320 is fully approved against Specification M-942 of the Association of American Railroads for Journal Roller Bearings Grease for non-field lubricated bearing applications. It is used by major manufacturers of railroad journal bearings as the factory-fill lubricant. Mobil Arapen RB 320 has an application temperature range of -20º C to + 120º C.


Features and Benefits

Mobil Arapen RB 320 railroad car journal bearing grease offers the following features and benefits:

  • Approved against AAR specification AAR-942
  • Formulated for long service life over a wide range of climatic conditions
  • Exhibits excellent oxidation stability, shear stability, seal compatibility, and water resistance for extended grease life and equipment integrity



  • Roller bearings of railroad car journals where no provision is provided for in-service re-lubrication.
  • Factory fill lubricant of major railroad journal bearing manufacturers


Specifications and Approvals

Mobil Arapen RB 320 has the following builder approvals: 


Typical Properties

Mobil Arapen RB 320 
NLGI Grade1.5
Thickener TypeLithium/Calcium soap
Color, VisualLight Amber
Penetration, Worked, 25º C, ASTM D 217305
Dropping Point, ºC, ASTM D 2265180
Viscosity of Oil, ASTM D 445 
cSt @ 100º C14.7
Penetration, ASTM D 217, Change from 60X to 100,000X, mm/10+20
Emcor Rust, ASTM D 6138, Distilled Water0/0
Oxidation Stability, ASTM D 942: 
- pressure drop at 100 hrs, psi1
- pressure drop at 500 hrs, psi3


Health and 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 are trademarks of Exxon Mobil Corporation, or one of its subsidiaries.


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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
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