Mobil Pegasus™ 605 Ultra 40  

Mobil Industrial, Ireland

Gas Engine Oil

Product Description

Mobil Pegasus™ 605 Ultra 40 is the latest generation of gas engine oil primarily intended for the lubrication of modern medium and high-speed four-cycle engines operating on landfill gas that contains contaminants such as hydrogen sulphide, halides or siloxane. Its formulation has been carefully balanced to provide extended oil drain intervals, control the formation of carbon and varnish deposits, with very good anti-wear and anti-scuff performance.


Features and Benefits

  • Exceptional oxidation stability, nitration resistance and thermal stability that help extend oil life, clean engines, reduce filter costs and resist deposit formation
  • Very good anti-wear characteristics help to reduce wear of engine components, reduce scuffing of liners in highly loaded gas engines and provide break-in protection
  • Extraordinary detergent-dispersant system provides protection of upper cylinder and valve train components, clean engines and long filter life
  • Optimized TBN and reserve alkalinity help protect valve seats and faces on four-cycle engines, improve spark plug performance, and reduce power loss from detonation



  • Engines operating on fuel containing corrosive materials such as TOHCl (Total Organic Halides as Chloride) such as landfill or biomass gas
  • Gas engines operating on fuel that contains moderate levels of hydrogen sulfide (H2S)
  • Spark ignited four-cycle gas engines with very low lube oil consumption
  • Medium and high speed four-cycle engines equipped with catalytic converters requiring a low ash gas engine oil
  • Reciprocating compressors operating on natural gas that contains sulphur or chlorine compounds


Specifications and Approvals

Mobil Pegasus 605 Ultra 40 meets or exceeds the requirement of:

Mobil Pegasus 605 Ultra 40 has the following builder approvals:
GE Waukesha Engine Landfill Gas Applications
MWM GmbH TR 0199-99-2105
GE JENBACHER TI 1000-1109 (Class B fuel gas, Series 2 & 3)
GE JENBACHER TI 1000-1109 (Class B fuel gas, Series 4A, 4B & 4C)
GE JENBACHER TI 1000-1109 (Class B fuel gas, Series 6 up to version E)

GE JENBACHER TI 1000-1109  (Class C fuel gas, Series 2 & 3)

GE JENBACHER T 1000-1109  (Class C fuel gas, Series 4A & 4B)

GE JENBACHER TI 1000-1109  (Class C fuel gas, Series 6 up to version E)

GE JENBACHER TI 1000-1109 (CAT (catalyst) approved)
Caterpillar Energy Solutions TR 2105, Lube Oils for Gas Engines ( CG132, CG170, CG260)
MAN M 3271-4



Typical Properties 

Mobil Pegasus 605 Ultra 40  
SAE Grade
Viscosity, ASTM D 445
cSt @ 40 ºC 137.5
cSt @ 100 ºC 15.0
Viscosity Index, ASTM D 2270 110
Sulphated Ash, wt%, ASTM D 874 0.6
TBN #, mg KOH/g, ASTM D 2896 5.3
Pour Point, ºC, ASTM D 97 -21
Flash Point, ºC, ASTM D 92 268
Density @ 15.6 ºC, ASTM D 4052, kg/L 0.85

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


Esso Petroleum Company limited
ExxonMobil House, Ermyn Way, Leatherhead, Surrey KT22 8UX

44 (0)1372 222000

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.