Mobilgard™ M50 diesel engine oil

Related product

Mobilgard™ M30 Series diesel engine oils

Mobilgard™ M30 Series diesel engine oils are recommended for use in medium-speed engines in deep-sea, coastal and river vessels operating on heavy fuel oil (HFO).

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Data sheets

Deep Sea Shipping Industry
Cruise and Ferry
Extended Life
Enhanced Wear Protection
Corrosion protection

Product information

Features and Benefits

Mobilgard M50 has industry-leading 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 superior lube/fuel compatibility and separates easily from water. 

When used as recommended, Mobilgard M50 diesel engine 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 M50 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 new oil is the result of an extensive research and development program, incorporating ExxonMobil's patented DAC (Detecting Aspahltene Contamination) Test. 

Mobilgard M50 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 is especially beneficial in engines having low crankcase oil consumption or operating with low cylinder liner temperatures. In these engines, oil life and drain intervals have been significantly reduced when using conventional lube oils due to severe TBN depletion resulting from very low lube oil consumption. Relatively high alkalinity reserves in this oil provide 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. 

Mobilgard M50 is also recommended for topping-up existing oil charges with a low TBN value to raise them to an acceptable value.

Typical Properties

SAE Grade 40
Specific Gravity at 15ºC 0.922
Flash Point, ºC, ASTM D 92 228
Pour Point, ºC, ASTM D 97 -6
Viscosity, ASTM D 445

cSt, at 100ºC 14
TBN, mg KOH/g, ASTM D 2896 50
Sulphated Ash, wt%, ASTM D 874 6.5
  • Mobilgard™ M50 reduces oil consumption and extends oil change intervals

    Princess Cruises was able to extend oil change intervals and save over 80,000 litres of oil, reducing operating expenses across seven ships with Mobilgard™ M50 engine oil.

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    Our services help reduce feed rates and consumption, helping increase the reliability of shipboard equipment and minimise maintenance costs.

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