The Effect of Multigrade Oil Rheology on Friction in Dynamically Loaded Bearings

A range of multigrade oils designed for both gasoline and diesel engine operation have been characterised in terms of their load bearing capacity (LBC) and hydrodynamic friction (torque) under transiently loaded conditions using a journal bearing simulator. Base oil behaviour was also investigated. The results suggest that while LBC and torque are viscosity dominated, it is possible to decouple transiently loaded journal bearing LBC and hydrodynamic torque by modification of the bulk lubricant rheology.

It would now appear possible that both LBC and frictional benefits may be obtained by from multigrade oils by judicious choice of lubricant base oil and additive systems.