This paper outlines the history and background of the NLGI (formerly known as the National Lubricating Grease Institute) lubricating grease specifications, GC-LB classification of Automotive Service Greases as well as details on the development of new requirements for their High-Performance Multiuse (HPM) grease certification program.
The performance of commercial lubricating grease formulations through NLGI's Certification Mark using the GC-LB Classification system and the recently introduced HPM grease certification program will be discussed. These certification programs have provided an internationally recognized specification for lubricating grease and automotive manufacturers, users and consumers since 1989. Although originally conceived as a specification for greases for the re-lubrication of automotive chassis and wheel bearings, GC-LB is today recognized as a mark of quality for a variety of different applications. The main driving force to upgrade GC-LB was that six of the 12 property test methods utilized in ASTM D4950 had major issues, requiring either revised, alternative or new test methods. In addition to the issues associated with the test methods, NLGI recognized that advancements in materials, technologies and applications would be better served by newer specifications. The initiative that began as an update to the GC-LB specification then led to the introduction of the HPM specifications.
Analysis of GC-LB certified greases showed that most commercial greases also claimed other enhanced properties such as high load carrying, saltwater rust resistance, water resistance and long life in addition to meeting the GC-LB requirements. By 2019, NLGI’s Specification Working Group had developed a draft specification with proposed changes to upgrade the GC-LB classification. This draft was further modified through interviews, surveys and in-depth discussion with members of the lubricating grease industry. The initial focus was on updated specifications for a High-Performance Multiuse grease that could be used in a variety of bearings and applications which require similar lubricating properties. Additional specifications were defined as part of the HPM specification for all these properties except long life. Long life (+LL) and High Temperature (+HT) properties are currently being addressed in Phase 2 of the HPM Grease Certification Program. Additionally, the low temperature specification was added to the HPM specification after interest was shown during the interview and feedback process.
