Design Considerations in Formulating Gasoline Engine Lubricants for Improving Engine Fuel Economy and Wear Resistance Part I: Base Oils and Additives

It is generally accepted that significant gains in fuel economy can be accomplished by reducing friction between the moving surfaces in key engine components (e.g. valvetrain, piston, crankshaft). This paper provides an overview of how specific tribological/rheological properties (e.g. viscosity, volatility, friction coefficient, film thickness, wear volume) can be considered in the design of fuel efficient crankcase engine lubricants that promote high wear resistance. Here, an example in how base stock, viscosity modifier (VM) and friction modifier (FM) can impact the surface friction is given. Friction and wear measurements from bench level lubrication characterization test methods mainly, high frequency reciprocating rig (HFRR) and mini-traction machine (MTM), are presented.