The Essential Guide to Understanding Industrial Lubricant Specs

Industrial lubricants are oils or greases that decrease friction and wear while forming a protective film between moving surfaces. Grease is base oil plus additives held in a thickener matrix. Thus, it stays put for intermittent, stop-start service and sealed parts. Oil circulates, carries heat away, and flushes contaminants, which suits high-speed systems for flow. Grease dominates applications with rolling bearings, pins, and bushings where retention and sealing matter. On the other hand, oil is common in circulating and hydraulic systems and preferred for chain drives.

In this post we often refer to ASTM, which is the American Society for Testing and Materials, now known as ASTM International. They develop and publish technical standards for materials, products, systems, and services. In lubrication, ASTM test methods define how properties are measured so results are consistent across labs and manufacturers.

Core Industrial Lubricant Specs:

NLGI Grade (Consistency):

NLGI grade classifies grease "soft to hard" by the worked cone penetration at 25°C using ASTM D217. Grades are from 000 (very fluid) to 6 (very hard). Match consistency to component clearances, sealing, and how the grease will be dispensed or pumped. A softer grade can migrate and purge faster. At the same time, a very firm grade can resist leakage but may not feed well into tight contacts. Treat the NLGI grade as a handling and placement property, not as oil viscosity or load rating. This is a foundational element in comparing industrial lubricant specs. 

Thickener:

The thickener forms the grease's sponge-like structure that traps and releases base oil. Systems include lithium and lithium-complex soaps, calcium sulfonate complex, aluminum complex, polyurea, and non-soap types such as organoclay and silica. Thickener chemistry affects mechanical stability, heat resistance, water tolerance, and inherent EP or antiwear behavior. Selection is often dictated by compatibility with legacy greases and by the needed certifications.

Base Oil & Viscosity:

Base oil type (mineral, PAO, synthetic, ester, PAG, etc.) influences low-temperature flow, volatility, and oxidation behavior. Viscosity governs film thickness at operating temperature. Industrial oils are specified by ISO VG per ISO 3448, which defines kinematic viscosity grades at 40°C with ±10% bands and 50% steps between grades. Choosing the right ISO VG optimizes film strength, speed, load, and temperature.

Operating Temperature Range:

Usable temperature range depends on base-oil type or viscosity, thickener, and antioxidant package. A grease's dropping point is not its continuous upper service limit. Yet, dropping point is a static softening event, and many greases should be run well below it. Low-temperature limits are set by base-oil viscometrics and rheology, which also impact startup torque and feed in automated systems. 

Dropping Point:

Dropping point is the temperature where grease softens under heat and releases its first drop of liquid oil. It is an identification and quality-control metric. It helps differentiate thickener families and detect manufacturing shifts but has limited relevance to real service where shear, purge, contamination, and ventilation alter thermal behavior. Don't use it alone to determine the maximum operating temperature. 

Load / Extreme-Pressure (EP) Performance:

The Four-Ball EP test (ASTM D2596) increases load on three stationary balls against a rotating ball until failure, reporting values like weld load, last non-seizure load, and load-wear index. These results indicate how well a grease protects under extreme pressure, but they don’t directly predict real-world service life. Treat them as screening tools alongside viscosity, thickener, and surface speeds when you interpret industrial lubricant specs. The ASTM D2266 (Four-Ball Wear test) is often paired with the D2596 in lubricant spec sheets. 

Water Resistance (Washout):

ASTM D1264 measures how easily grease is washed from a bearing by a water jet at definite temperature and flow. Results are reported as mass percent lost, and lower mass loss indicates better retention. The test does not duplicate every service condition, but is worthwhile for ranking greases for wet ends, splash zones, and outdoor equipment. 

Corrosion & Rust Protection:

ASTM D1743 checks the capacity of a grease to avoid rust on tapered roller bearings under wet conditions. Bearings are packed, exposed, and inspected for corrosion, which allows a pass/fail or rating that highlights protective performance in storage or intermittent-duty environments. Use it with other water-related tests when specifying for humid or washdown service. 

Oxidation Stability (Grease Life):

ASTM D942 finds resistance to oxidation while holding grease in an oxygen-pressurized vessel at higher temperatures and tracking pressure drop over time. Lower pressure loss means stronger oxidative stability and supports longer relube intervals in compatible applications. Treat D942 as a comparative lab indicator that complements bearing-life and high-temperature endurance tests.

Pumpability:

Pumpability is the ability of a grease to flow through lines, valves, and fittings under pressure. It depends on apparent viscosity at moderate shear, which captures the combined effects of grade, base-oil viscosity, thickener, and temperature. ASTM D1092 quantifies apparent viscosity for steady-flow calculations and helps predict pressure drops and low-temperature feed in centralized systems. This is critical when selecting grease for long lines or small orifices in automated delivery systems.

Other Specs

• Additives and Solids (MoS2): MoS2 and graphite are solid lubricants that support boundary lubrication at low speeds and high loads while forming low-shear films on metal surfaces. Use them when contact is severe or a start-stop is recurrent.
• Certifications and Classifications: For hygienic applications, look for NSF H1 registration and ISO 21469 certification. They address composition and manufacturing hygiene for lubricants with incidental food contact. ISO 6743-9 and DIN 51502 provide standardized grease classification and designation for identification. 
• Mixing and Compatibility with Other Lubricants: Avoid mixing greases unless verified compatible. Differences in thickener, base oil, or additives can cause softening, bleeding, or failure. Compatibility charts are only guides in industrial lubricant specs. You should plan a full purge or flush when switching products. 
• Environmental Attributes (Biodegradability): "Readily biodegradable" means attaining more than 60% degradation within 28 days in an OECD 301 test (with a 10-day window for most methods). Check the specific method cited on the data sheet.

How to Pick?

Follow the equipment maker's lube spec first. If the OEM names a product standard, NLGI grade, thickener, base-oil family, or ISO VG, match those exactly. On the other hand, if you must choose yourself, treat the original recommendation as the template and pick the closest match on NLGI, thickener chemistry, base oil, or ISO VG, and the stated continuous operating temperature. Compare the data sheets and line up these industrial lubricant specs side-by-side. 

If you've read this post because you're trying to determine which lubricant to use inside your auto greasers, you may want to check out our other post; Choosing the Right Auto Greaser: A Simple Guide. For hands-off, spec-compliant delivery of grease or oil, make sure to visit our Auto Greasers collection.