Gas Engine Oil

Mobil Pegasus™ 1 is a high performance synthetic gas engine oil designed to meet the highest performance requirements of the most demanding naturally aspirated and turbocharged stoichiometric and lean-burn gas engines. It is formulated from wax-free synthetic base oils and a balanced additive system to provide performance that is unattainable with conventional mineral oil-based gas engine oils. The potential benefit is an improved bottom line through improved engine and oil life, reduced maintenance costs and lower fuel costs.

The unique formulation of Mobil Pegasus 1 minimises ash deposits, piston land and ring belt deposits, liner scuffing, and valve seat and valve face wear. It has outstanding resistance to oxidation and the inherently high viscosity index of the synthetic base oil components ensure a protective lubricant film at high temperatures well above the limit for mineral oil-based products. Mobil Pegasus 1 exhibits low volatility, a performance characteristic that helps reduce oil consumption and improve valve lubrication performance measurably. Its unique viscometrics and low traction coefficient reduce power losses and provide potential fuel economy benefits, particularly under variable load, speed and temperature conditions.

Features and Benefits

The state-of-the art technology used in Mobil Pegasus 1 is designed to provide a high level of engine performance in a wide range of high-output gas engines. Its outstanding oxidation resistance and thermal stability provide extended service life for both the engines and the oil. In addition, the unique properties of Pegasus 1 will result in lower internal friction under cold start-up and hot running conditions resulting in reduced wear and potentially lower fuel consumption. The use of this product will result in lower maintenance costs through its extended service life capability, reduced filter costs and improved engine life.

FeaturesAdvantages and Potential Benefits
Balanced Synthetic FormulationExtended drain intervals and improved engine life
Longer filter life potential
Cleaner engines
Outstanding Oxidation and Thermal StabilityReduced levels of ring land and ring groove carbon
Improved valve guide performance
Lower levels of carbon/coking deposits
Excellent High and Low Temperature PerformanceEffective lubrication under cold startup conditions
Easier engine cranking at low temperatures
Improved engine protection under high temperature conditions
Naturally High Viscosity IndexWide temperature performance
Low VolatilityReduced oil consumption
Reduced deposit formation in critical engine areas
Exceptional Anti-wear and Anti-scuff ProtectionResists wear and scuffing of liners and pistons particularly in high BMEP engines
Low Traction CoefficientPotential for lower fuel costs
Improved engine power
Easier starting


  • Mobil Pegasus 1 is recommended for a wide range of gas engine models.
  • The product is particularly suited for high speed, four-cycle turbocharged and naturally aspirated gas engines requiring a nominal 0.5% ash gas engine oil.
  • It is an excellent lubricant for both stoichiometric and lean-burn designs
  • It is ideally suited for cogeneration and ebullient cooled applications because of its wide temperature range capability and extended engine protection and long oil life.
  • Mobil Pegasus 1 is fully compatible with all seals commonly used in gas engines and with mineral oils but admixture with mineral oils will lower the performance benefits that can be obtained from this outstanding lubricant
  • May be used with gas engines using alternative energy sources for fuel gas containing up to 0.3% sulphur as hydrogen sulphide

Specifications and Approvals

Mobil Pegasus 1 has the following builder approvals:
MAN: M 3271-1
MAN: M 3271-2
MWM GmbH TR 0199-99-2105, Lube Oils for Gas Engines
WAUKESA: 12V / 18V 220 GL Applications

Mobil Pegasus 1meets or exceeds the requirements of :


Typical Properties

Mobil Pegasus 1
SAE GradeSAE 15W-40
Viscosity, ASTM D 445
cSt @ 40º C93.8
cSt @ 100º C13.0
Viscosity Index, ASTM D 2270137
Sulfated Ash, wt%, ASTM D 8740.5
Total Base #, mg KOH/g, ASTM D 28966.5
Pour Point, ºC, ASTM D 97-48
Flash Point, ºC, ASTM D 92238

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.


It cannot be guaranteed that the product information given above is up to date. For the latest version of the Product Data Sheet we refer to the product library of ExxonMobil.