Mobil Rarus 800 Series

Air Compressor Lubricants

The Mobil Rarus™ 800 Series is a line of supreme performance air compressor lubricants primarily intended for the lubrication of severe duty reciprocating air compressors but not recommended for air compressors used in breathing air applications. They are engineered to meet or exceed the stringent requirements of the major compressor manufacturers. They are formulated with design-specific synthetic base-oils and a high technology additive system that assures exceptional equipment protection and reliability for compressors operating under conditions where mineral-oil based products are not meeting expectations. Mobil Rarus 800 Series provides excellent wear protection and outstanding resistance to oxidation and thermal degradation, greatly superior to mineral oils. Their unique formulation provides the ability to help reduce maintenance costs through minimising equipment problems and downstream deposits and carryover.


Mobil Rarus 800 Series lubricants significantly reduce the potential for fires and explosions, compared to mineral oil-based products. They exhibit a virtual absence of deposit formation and higher autogenous ignition temperatures improving both performance and safety. Their exceptional water separating characteristics reduce problems with emulsion formation and carryover into downstream piping and equipment. They are recommended or approved by many of the leading compressor manufacturers.


Features and Benefits

The use of the Mobil Rarus 800 Series oils can result in cleaner compressors and lower deposits compared to conventional mineral oils, resulting in longer running periods between maintenance intervals. Their excellent oxidation and thermal stability safely allow extended life capability while controlling sludge and deposit formation. They possess outstanding anti-wear and corrosion protection, which enhances equipment life and performance.



Advantages and Potential Benefits

High Performance Synthetic Base Stocks

Significant performance capabilities relative to mineral oils

Improved safety

Low Ash and Carbon Formation

Improved valve performance

Reduced deposits in discharge lines

Reduced potential for fires and explosions in discharge systems

Improved compressor performance

Outstanding Oxidation and Thermal Stability

Longer oil life

Improved filter life

Lower maintenance costs

High Load-carrying ability

Reduced wear of rings, cylinders, bearings and gears

Excellent Water Separability

Less carryover to downstream equipment

Reduced sludge formation in crankcases and discharge lines

Reduced blockage of coalescers

Less potential for emulsion formation

Effective Rust and Corrosion Protection

Improved protection of valves and reduced wear of rings and cylinders



The Mobil Rarus 800 Series oils are recommended for single and multistage air compressors, but are not recommended for air compressors used in breathing air applications. They are particularly effective for continuous high temperature operation with discharge temperatures up to 200ºC. They are suitable for reciprocating and rotary type machines with the lower viscosity grades mainly used in rotary compressors. Rarus 800 Series oils are recommended for units with a history of excess oil degradation, poor valve performance or deposit formation. They are compatible with all metals used in compressor construction and with mineral oil-based lubricants but admixture will detract from their performance capabilities. Mobil Rarus 800 Series oils are compatible with seals made from fluorinated hydrocarbon, silicone, fluorosilicone, polysulfide, Viton, Teflon, and high nitrile Buna N NBR (above 36% acrylonitrile) materials. Materials not recommended include low nitrile Bune N NBR (below 30% acrylonitrile), natural and butyl rubbers, Neoprene, polyacrylate, styrene/butadiene and chlorosulfonated polyethylene.


Oil resistant paints are not affected by Mobil Rarus 800 Series, but lacquer, varnish, pvc and acrylic paints are not recommended.


The following types of compressor applications have shown excellent performance with the Mobil Rarus 800 Series oils:

     •  All types of air compressors but specifically recommended for reciprocating air compressor

     •  Units operating under severe conditions

     •  Multistage units with a history of excessive oil degradation from mineral oil-based products

     •  They can be used for cylinder and crankcase lubrication

     •  Compressor systems with critical gears and bearings

     •  Compressors used in stationary and mobile applications


Properties and Specifications






ISO 32

ISO 100

ISO 150

Copper Strip Corrosion, 3 h, 121 C, Rating, ASTM D130




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




Foam, Sequence I, Stability, ml, ASTM D892




Foam, Sequence I, Tendency, ml, ASTM D892




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




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




Pour Point, °C, ASTM D5950




Rust Characteristics, Procedure A, ASTM D665




Total Acid Number, mgKOH/g, ASTM D974




Total Acid Number, mgKOH/g, ASTM D974(mod)




Viscosity Index, ASTM D2270





Health and Safety

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