Mobil Rarus™ 424J

Mobil industrial , Japan

Long-life oil cooled screw compressor oil

Product Description

The Mobil Rarus™ 424J is a long-life compressor oil with significantly improved oxidation and thermal stability and sludge resistance to meet the stringent performance requirements for lubricants such as achieving of high efficiency in package type oil cooled screw compressors and reduction in size and increase in the load.

The Mobil Rarus 424J has a good blending balance between highly-purified premium-quality base oil and several kinds of special additives, helping to control the formation of sludge due to oxidative degradation of oil under high temperature and constantly keep the inside of the system clean, also the product has the excellent water separability which facilitates the drain discharging. These features provide outstanding longer life compared to conventional screw compressor oils.

Features and Benefits

The use of the Mobil Rarus 424J can result in maintaining of cleaner compressors and lower deposits, resulting in longer running periods between maintenance intervals compared to conventional mineral oils. The significantly improved oxidation and thermal stability allow outstandingly longer oil life while controlling sludge and deposit formation under high temperature. This product has prominently excellent oxidation stability and corrosion protection, which enhances equipment life and performance.

Features Advantages and Potential Benefits
Excellent oxidation and thermal stability, and sludge resistance ‑ Reduced oil agent cost due to long-life oil that can bear long period of use
‑ Reduced system failure due to degradation of lubulicant oils and loss due to stopping of operation
‑ Reduced frequency of filter replacements, oil cooling system cleaning works, etc., replacement parts cost and labor cost
‑ Reduced potential for dangerous fires and explosion accidents
Excellent emulsion resistance and water separability ‑ Reduced maintenance expenditures due to easy separation and discharging of condensed  water contents in an oil tank
‑ Reduced maintenance labor cost
Excellent rust and corrosion protection ‑ Preventing rusts due to condensed water contents in an oil tank and preventing corrosion of copper or aluminum parts
‑ Longer equipment life
‑ Reduced maintenance labor cost



The Mobil Rarus 424J is suitable as lubricant for stationary package type oil cooled screw compressors and mobile oil cooled screw compressors. Also, this product can be used as lubricant for oil cooled rotary vane compressors. This product is particularly effective for continuous high temperature operation.

The Mobil Rarus 424J is not designed and intended for use in air compressors for breathing applications. Also, it is not recommended for use for such applications.

Due to its excellent oxidation and thermal stability, it is also used as heat medium for closed systems.

The Mobil Rarus 424J shows excellent performance with the following types of compressors:

  • Oil cooled rotary screw compressors
  • Oil cooled rotary vane compressors
  • Stationary and mobile package type compressors


Typical Properties

Mobil Rarus 424J
ISO Viscosity Grade 32
Viscosity, @ 40ºC, mm2/s , JIS K2283 30.95
Viscosity, @ 100ºC, mm2/s , JIS K2283 5.595
Viscosity index, JIS K 2283 120
Appearance clear
Pour Point, ℃, JIS K2269 -32.5
ASTM colour, JIS K2580 L0.5
Demulsibility, Time to emulsion formation to zero,minutes, JIS K2520 10
Foam Test, Seq I Tendency / Stability, ml, JIS K2518 10/0
Copper Strip Corrosion, JIS K2513, 3 h @ 100º C 1B
RPVOT, minutes, ASTM D2272 3360
Density, @ 15º C, JIS K2449 0.8506
Flash Point, ℃, COC, JIS K2265 236


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.

All trademarks used herein are trademarks or registered trademarks of Exxon Mobil Corporation or one of its subsidiaries unless indicated otherwise.


ExxonMobil Japan Godo Kaisha

Shinagawa Grand Central Tower

2-16-4, Konan, Minato-Ku,

Tokyo, 108-8218,


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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