Product Description

The Mobil Rarus 400 Series is a line of premium performance ashless air compressor lubricants designed to meet the stringent requirements of the major compressor manufacturers. They are formulated with high quality mineral base-oils and a high performance additive system designed to provide exceptional equipment protection and reliability for compressors operating under mild to severe conditions. They provide excellent wear protection and the ability to reduce maintenance costs through minimising equipment problems and downstream deposits and carryover. Because of their high FZG Ratings, the Mobil Rarus 400 Series make outstanding lubricants for compressor systems employing gears and bearings making them an excellent selection for crankcases as well as cylinder lubricants.

Features and Benefits

The use of the Mobil Rarus 400 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.

Features Advantages and Potential Benefits
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 400 Series oils are recommended for single and multistage air compressors. They are particularly effective for continuous high temperature operation. The maximum compressed air temperature, according to DIN 51506, is 220 °C. They are suitable for reciprocating and rotary type machines with the lower viscosity grades mainly used in rotary compressors. Rarus 400 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 compatible elastomers used in seals, O-rings and gaskets.

Mobil Rarus 400 Series oils are not intended or recommended for use in air compressors for breathing applications.

The following types of compressors have shown excellent performance with the Mobil Rarus 400 Series oils:

•  Reciprocating air compressor crankcases and cylinders

•  Rotary screw compressors

•  Rotary vane compressors

•  Axial and centrifugal compressors

•  Compressor systems with critical gears and bearings

•  Compressors used in stationary and mobile applications

Specifications and Approvals

This product meets or exceeds the requirements of: 424 425 426 427 429
DIN 51506:1985-09 VDL X X X X X

Properties and Specifications

Property 424 425 426 427 429
Grade ISO 32 ISO 46 ISO 68 ISO 100 ISO 150
Ash, Sulfated, mass%, ASTM D874 ‹0.01 <0.01 <0.01 <0.01 <0.01
Copper Strip Corrosion, 3 h, 100 C, Rating, ASTM D130 1B 1B 1A 1B 1A
Density @ 15 C, kg/l, ASTM D1298 0.866 0.873 0.877 0.879 0.866
FZG Scuffing, Fail Load Stage, A/8.3/90, ISO 14635-1 12 11 12 11 11
Flash Point, Cleveland Open Cup, °C, ASTM D92 236 238 251 264 269
Foam, Sequence I, Stability, ml, ASTM D892 0 0 0 0 20
Foam, Sequence I, Tendency, ml, ASTM D892 10 20 0 30 430
Kinematic Viscosity @ 100 C, mm2/s, ASTM D445 5.4 6.9 8.9 11.6 14.7
Kinematic Viscosity @ 40 C, mm2/s, ASTM D445 32 46 68 104.6 147.3
Rust Characteristics, Procedure A, ASTM D665 PASS PASS PASS
Rust Characteristics, Procedure B, Rating, ASTM D665 PASS PASS PASS
Rust Prevention, Procedure B, Rating, ASTM D665 PASS PASS
Viscosity Index, ASTM D2270 105 105 105 100 100

Health and Safety

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


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.