Application of a Split Lubrication Gasoline Engine to the Screening and Understanding of Friction Modifier Behaviour
Abstract:
A series of viscous and surface friction modifier additives has been studied in a
modified SI engine with separable valve train lubrication. From the results, it
has been possible to classify the hydrodynamic or boundary lubrication nature of
the observed effects for a series of lubricant additives. It is shown that the
frictional benefit of a given additive depends not only on the engine operating
condition but also on the engine components on which it is acting. For some
additives a fuel economy benefit can switch to a disbenefit as operating regime
changes and a different aspect of the additive properties becomes important.
Such observations are rationalised in the context of conventional lubrication
theory.