SAM Compressor Controller Model R — air compressor oil types and viscosity grades

Air Compressor Oil Types and Viscosity Grades

Air compressor oil comes in three base types and three common viscosity grades. This guide compares the types and the grades. It also lists the properties that separate a good oil from a poor one.

Oil base types

  • Mineral oils. Cost-effective, with a limited lifespan.
  • Synthetic oils. Better performance and longer life, at a higher price.
  • Semi-synthetic blends. A balance of performance and cost.

For most industrial applications, full synthetic oils offer the best overall value.

Viscosity grades

  • ISO 32 suits colder environments.
  • ISO 46 suits moderate climates and is the most common grade.
  • ISO 68 suits hot environments.

Choose a viscosity that matches the operating temperature and the compressor specification.

Oil properties that matter

Look for these characteristics on the data sheet:

  • High oxidation resistance
  • Good thermal stability
  • Low foaming tendency
  • Good water separation
  • Rust and corrosion protection
  • Extended drain intervals

Full synthetic oils typically score well in every area on this list.

Food-grade oils

Food, beverage, and pharmaceutical applications need food-grade lubricants that meet regulatory standards. Oil-free compressors also use food-grade lubricants for their bearings.

Related reading

Sources

  • Bloch, H. P. (2000). Practical Lubrication for Industrial Facilities. Lilburn, GA: The Fairmont Press.
  • Kaeser Compressors. (2022). Guide to Compressor Oils and Lubricants. Fredericksburg, VA: Kaeser Compressors, Inc.
  • Atlas Copco. (2021). Compressed Air Manual (8th ed.). Nacka, Sweden: Atlas Copco AB.