Low Temperature Pumpability in Gasoline Engines: Establishing Performance at Critical Locations

Abstract

An extensive series of low temperature cold room pumpability studies has been conducted in gasoline engines. Much of the work, although focusing on the role of the Viscosity Index (VI) Improver in SAE 5W-30 and SAE 10W-30 engine oils, has also addressed the issue of measuring oil performance at critical engine locations. In anticipation of an industry-wide re-evaluation of low temperature engine oil pumpability, it is hoped that this work can help the industry refine the Mini-Rotary Viscometer (MRV), and other bench test procedures. A correlation with critical oiling, rather than the generation of oil pressure at the oil sensor light location which is the basis for the pumpability component of the SAE J300 classification, would improve the system. It is clear from this work that the time to generate oil pressure at the oil filter is considerably shorter than the time it takes to generate oil pressure, or oil flow, at critical locations downstream. It is also clear that oil formulation plays a significant role in the low temperature pumpability performance. The engines evaluated in this work were a 2.2 L I-4 OHC, a 2.3 L I-4 OHC and a 3.8 L V-6 push rod engine.