Product Description

Developed specifically for medium-speed engines

Mobilgard™ M440 is a high performance 40 BN engine oil recommended for use on deep-sea vessels, coastal and river ships operating on heavy fuel oil (HFO).

This product provides:

  • Excellent high temperature oxidation
  • Outstanding residual fuel compatibility
  • Good thermal stability
  • Low volatility
  • High load carrying properties
  • Outstanding corrosion protection.

Corrosion protection

Mobilgard M440’s gh alkalinity reserves provide superior protection in neutralising the strong acids resulting from the use of high sulphur fuels, reducing corrosion and in turn maintenance and repair costs.

Unsurpassed engine cleanliness and protection

Mobilgard M440 oil offers excellent BN retention and resistance to viscosity increase, helping to maximise component life and cleaning intervals as well as minimise filter changes and purifier maintenance. It also:

  • Helps protect piston under-crowns from deposits caused by raw fuel dilution
  • Optimises the life of critical wear surfaces through outstanding anti-wear properties
  • Minimises oil consumption thanks to low volatility base stocks

Features and Benefits

Mobilgard M440 oil has outstanding thermal and oxidation stability. It has excellent TBN retention and resistance to viscosity increases over long operating periods. It also promotes a high level of engine cleanliness with protection against wear. Compared to other medium speed engine oils, it has excellent lube/fuel compatibility and separates easily from water.

When used as recommended, Mobilgard M440 oil provides the following benefits:

Features Advantages and Potential Benefits
Excellent thermal and oxidation stability Reduced deposits in piston undercrown and ring belt areas
Improved anti-wear properties Extends the life of critical wear surfaces
Advanced detergency/dispersancy Clean camshaft and crankcase spaces
Outstanding rust and corrosion properties Protects wear surfaces from water and acidic corrosion
High residual fuel compatibility Reduced sludge formation, longer oil life, cleaner engines
Low volatility base stocks Reduced lubricant consumption
Excellent TBN reserve and retention Combats fuel/combustion related corrosion and deposits


Mobilgard M440 oil can be used in most medium-speed trunk piston engine applications. It is recommended for use in main propulsion and auxiliary engines on deep-sea vessels; in main propulsion engines on coastal and river ships; and in stationary power plants. This oil is the result of an extensive research and development program, incorporating ExxonMobil’s patented DAC (Detecting Asphaltene Contamination) Test.

Mobilgard M440 oil is designed to meet the needs of engines operating on heavy fuel. It is recommended for use in the latest model medium speed diesel engines and are especially beneficial in engines having low crankcase oil consumption or operating with low cylinder liner temperatures. Relatively high alkalinity reserves in this oil provides superior protection in neutralising the strong acids resulting from the use of high sulphur fuels that find access to the crankcase to promote oil degradation and ring, cylinder, and bearing corrosion.

Typical Properties



SAE Grade


Specific Gravity at 15ºC


Flash Point, ºC, ASTM D 92


Pour Point, ºC, ASTM D 97


Viscosity, ASTM D 445

cSt, at 100ºC


TBN, mg KOH/g, ASTM D 2896


Sulphated Ash, wt%, ASTM D 874


Health and Safety

Based on available information, this product is not expected to produce adverse effects on health when used for the intended application, following the recommendations provided in the Material Safety Data Sheet (MSDS). MSDSs are available upon request through your sales contract office, or via the Internet on 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.