Aviation piston engine lubricating oils undergo extensive testing prior to their approval for use. During the revision of MIL-L-22851/J-1966 specifications, it was determined that a standardized engine test would be utilized. A Textron-Lycoming TIO-540-J2BD engine was selected as the engine for the 150-hour endurance test. Federal Aviation Regulation Part 33 served as the guideline for development of a standardized test specifically aimed at lubricating oil evaluation.This paper discusses this new 150-hour endurance test for piston engine lubricants used to gain SAE and MIL approval. This new test was conducted at the University of Illinois-Institute of Aviation during 1990.