Influence of Lubricating Oil Formulation on Winter Hot-Starting Engine Torque Requirements

The influence of lubricating oil formulation on the winter hot-starting torque requirements of an automotive engine was investigated in a four part study. Commercial multi-grade oils, V.I. improved oils, oils containing oiliness agents, and experimental oils in the new and used condition were evaluated for their low speed, hot cranking torque requirements. These torque requirements were determined using a test stand engine equipped to measure cranking torques at selected cranking speeds from 5–236 rpm. The ASTMD 445 viscosities at 210 F were shown to be inadequate for predicting the low speed, hot cranking torque requirements of the oils evaluated in this study. Several oiliness agents effectively reduced the low speed, hot cranking torque requirements of a crankcase oil.