Sequence VIB Engine Test for Evaluation of Fuel Efficiency of Engine Oils - Part II. Stage Selection and Time Factor Determination

The newly developed Sequence VIB engine dynamometer test for measuring the ability of engine oils to improve engine fuel efficiency was designed as an improvement on its predecessor, the Sequence VIA test. The Sequence VIB test features an additional, extended oil aging to correspond to aging of engine oils in certification vehicles and in customer use, and a new set of boundary/mixed and hydrodynamic lubrication stages to better represent a wider range of engines. Five fuel economy measurement stages were chosen for the Sequence VIB test from a larger set of prototype stages, based on extensive friction modeling of engines, analysis of Sequence VIA data on reference oils, and operational considerations. Time factors for these stages were derived based on a mini-mapping of engines considering engine operating conditions in the Metro/Highway Federal fuel economy test procedure (FTP M/H) and the estimated market volume of each engine-vehicle. Preliminary results suggest excellent comparison of the Sequence VIB results for new oils to Sequence VIA results, and more importantly, a good correlation of Sequence VIB results obtained after extended aging to vehicle performance at 6400-9600 km of pre-certification mileage accumulation.