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MobilGard™ is the flagship of marine engine oils from ExxonMobil. It is supported by over 60 years of engineering excellence and lubrication technology.

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Product information

   Mobilgard™ 300 C fact sheet 921.517 KB/pdf
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  • MAN
  • Wartsila
  • deep sea shipping industry
  • Enhanced Wear Protection
  • Wide Temperature

Technical resources

ExxonMobil launches next generation Mobilgard™ 300 C oil for slow-speed engines

ExxonMobil has recently launched Mobilgard™ 300 C oil, the latest high-performance system oil for two-stroke, crosshead marine diesel engines.

English, voyager newsletter,

ExxonMobil Launches Mobilgard™ 300 C marine system engine oil

ExxonMobil has launched Mobilgard™ 300 C, a high-performance system oil for two-stroke, crosshead marine diesel engines operating under severe conditions.

English, Press releases,

Features and Benefits

The high quality paraffinic base oils used in Mobilgard 300 C have excellent thermal stability and oxidation resistance. The formulation includes proprietary detergent and anti-wear additive systems to deliver enhanced crankcase cleanliness, along with excellent protection for highly-loaded engine parts. Mobilgard 300 C also provides good rust protection in case of water contamination, and excellent water separation characteristics.
When used as recommended in crosshead type diesel engines, Mobilgard 300 C system oil offers the following features and potential benefits:
Advantages and Potential Benefits
Enhanced detergency and improved thermal and oxidation stability Reduced deposits in piston cooling spaces
Better piston cooling efficiency
Cleaner crankcases and circulation tanks
Enhanced load-carrying and anti-wear performance Excellent protection for highly loaded engine components such as bearings and gears
Excellent rust and corrosion properties Longer bearing life
Protects critical bearing surfaces
Good water tolerance and separation capability Effective lubrication in the presence of water
Longer oil life due to efficient water separation


Mobilgard 300 C is recommended primarily for use as system oil in late model, high-output, crosshead diesel engines, especially those engines employing the system oil for piston cooling. It will prevent or reduce deposit formation in the piston cooling spaces, thus maintaining piston cooling efficiency and reducing the incidence of piston top burning and piston crown cracking. It will also prevent or reduce crankcase deposits and will provide outstanding protection for heavily loaded bearings and gears. Good rust prevention and water separation characteristics make Mobilgard 300 C an excellent system oil in older design crosshead diesel engines which have water-cooled pistons and where crankcase deposits can be a problem with lower-quality system oils.

Typical Properties

SAE Grade
Specific Gravity at 15ºC 0.8665
Flash Point, ºC, ASTM D 92 245
Pour Point, ºC, ASTM D 97 -24
Viscosity, ASTM D 445

cSt, at 40ºC 109
cSt, at 100ºC 11.9
Viscosity Index, ASTM D 2270 98
TBN, mg KOH/g, ASTM D 2896 9
Sulphated Ash, wt%, ASTM D 874 1.06
FZG Scuffing, Fail Load Stage, A/8.3/90, ISO 14635-1 12
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