Q1 2025 Spokesman Abstracts

Test Methods: A History of Their Development as Disclosed in the NLGI Spokesman

The NLGI Spokesman has been published since 1937, although back editions only become available starting in 1941. The Spokesman papers archived on the NLGI website provides a historical record of the development of grease technology over the decades. This paper is the final one in series of three. The previous two papers were: William Tuszynski, J. Andrew Waynick, “Grease Thickeners: A History of Their Development as Disclosed in the NLGI Spokesman”, NLGI Spokesman, Jan/Feb 2024. William Tuszynski, J. Andrew Waynick, “Base Oils and Additives: A History of Their Development as Disclosed in the NLGI Spokesman”, NLGI Spokesman, May/Jun 2024. This paper provides a summary of Spokesman papers as related to the development and evaluation of the major test methods used in the industry. Each of these test methods are discussed in turn starting with the early references covering the development and codification of the test, often as ASTM methods, followed by examples illustrating the use of the tests in grease development and application. The discussions provided in this paper as related to the numerous cited Spokesman papers are not comprehensive in their coverage. Only summaries are provided so as to allow the reader to determine if a full reading would be useful. Each major section has its own corresponding reference section at the end of the paper. This allows the reader to more easily research the areas of interest while not becoming entangled in areas of lesser interest. While not exhaustive, the information in this paper does serve as a valuable starting who wish to obtain a more complete understanding of this subject matter.

Viscosity Modifiers Versus Bearing Torque
in Greases With Re-Refined Oil

Re-refined base oils (RRBO) present a valuable opportunity for advancing sustainability in grease formulations, supporting a circular economy for lubricants. However, most re-refined oils are limited to ISO 15-46 viscosity grades, which are significantly lower than the ISO 220-460 grades typically required for grease applications. Viscosity modifiers can enhance RRBO to achieve higher viscosity grades, but their impact on grease rheology and load-carrying properties remains unclear.

This study builds on prior work where viscosity modifiers were used to successfully upgrade 25 cSt @ 40°C RRBO to ISO 220 base oil blends for NLGI HPM-HL multipurpose EP greases, showing performance comparable to control greases using Group I oils. This year’s focus shifts to the application of polymer-enhanced RRBO in bearing greases, where proper viscosity and viscosity ratio (kappa) are critical for optimal performance. While industrial fluid specifications such as ASTM D6158 and AGMA 9005 have incorporated high viscosity index (VI) formulations, current grease standards are primarily based on VI 80-100 Group I oils.

 In this study, the effects of increased VI and viscoelasticity introduced by viscosity modifiers were explored in sustainable bearing greases using RRBO at ISO 100. Viscosity modifiers, typically ranging from 10,000 to 200,000 g/mol, were compared with traditional synthetic base stocks like PAO and PIB, which have lower molecular weights. Bearing torque on 6204 deep groove ball bearings was measured and evaluated alongside apparent viscosity using a Brookfield CAP 2000 cone/plate viscometer. The goal was to understand the limits and impact of polymers on conventional bearing grease selection practices.

Assessment of the Lubricating Efficiency of Current Greases in Electric Vehicle Applications

The growing emphasis on environmental concerns and the implementation of stricter vehicle emission policies have led to a significant shift in transportation from traditional internal combustion engine vehicles (ICEVs) to more eco-friendly Electric vehicles (EVs). With the global growth of EVs, there has been a rapid increase in market value, designs, and manufacturers. However, this shift has also caused engineers to reevaluate their lubrication approach and determine if current gear oils, coolants, and greases formulated for ICEVs can still effectively meet the new lubrication requirements of this new technology. These new requirements include noise reduction, thermal transfer, seals and materials compatibility, lubrication efficiency in the presence of electrical current and electromagnetic fields generated by electric modules, sensors, and circuits. This paper will thoroughly analyze existing greases to determine if they meet the requirements and suggest potential paths for the development of future formulations.