Presentation Profile
Mechanical Shear-Induced Viscosity Loss in Polymer-Modified Lubricants: Evaluation with Use of Diesel Injector & Other Techniques
Currently Scheduled: 10/14/2026 - 1:00 PM - 2:00 PM
Room: Exhibit Hall Entrance
Main Author
Raj Shah - Koehler Instrument Company, Inc.
- Gavin Cunningham - Koehler Instrument Company, Inc.
Abstract:
Mechanical shear degradation is a crucial factor governing the lifetime performance of polymer-modified lubricating oils, specifically in applications where fluids are repeatedly subjected to high-stress circulation through pumps, injectors, bearings, and engine components. Under such conditions, mechanical scission of viscosity-modifying polymers can produce permanent reductions in kinematic viscosity, compromising film formation, load-bearing capacity, and wear protection. The Koehler K95791 Shear Stability Tester is a European diesel injector apparatus designed for controlled assessment of viscosity loss, providing a reproducible standardized shear stability evaluation (in accordance with ASTM D6278, ASTM D7109, IP 294, DIN 51382, and CEC L-14-93). The apparatus subjects the test fluid to repeated passage through a diesel injector nozzle, applying controlled mechanical stress through the incorporation of a fluid reservoir, a double-plunger injection pump, an atomization chamber, a pressure monitoring system, and a fluid cooling vessel to maintain defined operating conditions. By comparing pre- and post-shear kinematic viscosity at 100 °C, this method produces a quantitative measure of permanent viscosity loss. This loss is principally attributed to mechanical degradation, while limiting thermal and oxidative contributions. The resulting shear stability data yield essential information for lubricant formulation, polymer additive evaluation, quality control, and the comparative assessment of fluids intended for high-stress service environments. This methodical approach provides a reproducible structure for evaluating lubricant durability and supporting performance-based formulation decisions.
