Multiuse greases are required in a variety of different applications, many having different performance challenges. In specific applications, the grease may need to deliver enhanced levels of performance over the high-performance multiuse (HPM) core specification, such as increased long life (LL).

A multiuse grease offering longer life performance results in less re-greasing of components, providing both labor saving and environmental benefits.

While the HPM + LL specification has essentially been agreed, technical issues surrounding one of the integral tests, a new grease life test method, means this HPM enhanced category may not be introduced until at least 2023.

Despite this, this article provides a brief summary of the expected test requirements included in the HPM + LL specification.

Greases meeting the enhanced long life specification requirements will be awarded the HPM + LL certification mark. In order to meet this higher level of performance, a grease must first pass the HPM core specification. 

To demonstrate an enhanced level of long life performance over the HPM core specification, there are an additional seven test performance requirements.

• Oxidation stability test (ASTM D942), with tighter limits than the HPM core specification.
• Roll stability test (ASTM D1831), with tighter limits than the HPM core specification.
• Modified elastomer compatibility test (ASTM D4289), with tighter limits than the HPM core specification, as well as a more relevant elastomer used in long life applications.
• Four-ball wear scar test (ASTM D2266), with tighter limits than the HPM core specification and the same limits as the HPM + HL specification.
• Fretting wear loss test (ASTM D4170), with same limits as the HPM + HL specification.
• Fretting wear scar test (ASTM D7594), with same limits as the HPM + HL specification.
• A new grease life test, still under development, with limits still to be set.

Greases passing the enhanced performance category/categories allow grease marketers to use the approved certification mark on their products and in promotional materials, in line with NLGI’s terms of use.

Our View

While still under development, the HPM + LL enhanced category will provide the opportunity to market higher performing multiuse greases for applications which require enhanced levels of long life performance, above the HPM core specification.

In order to pass the more severe long life specification requirements, the grease lubricant will require careful re-formulation, such as higher-performing antioxidant and anti-wear additives.

The availability of HPM certified greases provides a true upgrade in performance levels, delivering tangible benefits to all stakeholders in the supply chain.

For more information on the NLGI HPM grease specification, visit our NLGI High-performance Multiuse (HPM) Specification section or contact your Lubrizol representative.