Engine Oil Fuel Economy: Benefits and Potential Debits of Low Viscosity Engine Oil 2019-01-2241

There has been a trend in the automotive industry toward the use of lower viscosity engine oils as fuel economy requirements become more demanding across the globe. Lower viscosity fluids may improve fuel economy due to their improved pumpability, lower churning losses, and thinner lubricating films. However, there is one important caveat related to the use of these fluids: the amount of improvement, if any, is hardware design and application dependent. Standard industry fuel economy tests and engines with differing designs may show divergent responses when using lower viscosity engine oils, not always showing an improved fuel economy response. This paper summarizes the work conducted by the authors to demonstrate how and why the inconsistent results in fuel economy can occur with low viscosity oils.