Mobil Pegasus 805 Ultra

Gas Engine Oil

Mobil Pegasus™ 805 Ultra is a high performance gas engine oil engineered to meet the rigorous demands of today's high output four-cycle engines designed to reduce emissions and improve fuel-efficiency. It meets a wide range of OEM requirements making it a great choice where high-speed four-cycle engines from various OEMs are used.


Mobil Pegasus 805 Ultra is designed to provide very good protection against piston scuffing, scoring and ring and liner wear. It also exhibits excellent resistance to foaming, good demulsibility and high-level corrosion protection. It is formulated with low levels of zinc and phosphorus making it compatible with engines equipped with catalytic converters.


Equipment lubricant recommendations

Data sheets

Technical resources

Features and Benefits

•  Extraordinary oxidation stability and nitration resistance provide cleaner engines, good oil life, and reduced oil disposal and filter costs

•  Very good anti-wear characteristics help to reduce wear of engine components and reduce scuffing of pistons and liners

•  Good corrosion resistance protects bearings and internal components

•  Extraordinary detergent-dispersant system provides protection of valve train components, cleaner engines and longer filter and spark plug life

•  Very good foam separation reduces potential negative effects of air on wear and oil degradation



     •  Caterpillar, Waukesha and other turbocharged, naturally aspirated, medium to high speed four-cycle engines requiring a low ash oil

     •  Four-cycle engines experiencing valve face and seat wear

     •  Lean-burn and stoichiometric four-cycle engines operating under high load, high temperature conditions

     •  High-speed four-cycle gas engines used in cogeneration applications

     •  Engines equipped with catalytic converters

     •  Applications using alternate fuels containing low levels of Sulphur or Chlorine

     •  In field gathering operations where sour gas (low levels of H2S) may be used as fuel


Specifications and Approvals


This product has the following approvals:

Caterpillar Energy Solutions TR 2105, Lube Oils for Gas Engines (CG132, CG170, CG260)

INNIO Waukesha Engine 220GL Applications Using Pipeline Quality Gas

INNIO Waukesha Engine Cogeneration / Gas Compression Applications Using Pipeline Quality Gas

MWM TR 0199-99-2105, Lube Oils for Gas Engines

Wartsila 20DF

Wartsila 31DF

Wartsila 31SG

Wartsila 32DF

Wartsila 34DF

Wartsila 34SG

Wartsila 46DF

Wartsila 50DF

Wartsila 50SG

Bergen Engines AS (former Rolls-Royce Bergen) C-Type Gas Engines

Bergen Engines AS (former Rolls-Royce Bergen) B 35:40 Gas Engines

Bergen Engines AS (former Rolls-Royce Bergen) K-Type Gas Engines


This product is recommended for use in applications requiring:



This product meets or exceeds the requirements of:



Properties and Specifications




SAE 40

Viscosity Index, ASTM D2270


Kinematic Viscosity @ 100 C, mm2/s, ASTM D445


Pour Point, °C, ASTM D97


Flash Point, Cleveland Open Cup, °C, ASTM D92


Density @ 15 C, kg/l, ASTM D4052


Ash, Sulfated, mass%, ASTM D874


Kinematic Viscosity @ 40 C, mm2/s, ASTM D445


Base Number - Xylene/Acetic Acid, mg KOH/g, ASTM D2896 


 (*) use of other ASTM approved solvents may yield different results.

Health and safety

Health and Safety recommendations for this product can be found on the Material Safety Data Sheet (MSDS) @