The fuel-saving capabilities of various experimental and commercial passenger car engine oils have been demonstrated in extensive studies. Lower viscosity oils and those containing friction-reducing additives have shown measurable fuel economy benefits in a wide range of laboratory and vehicle tests. Several test techniques are described for screening fuel-saving engine oils and components. Closely controlled chassis rolls and over-the-road vehicle tests are utilized to demonstrate the actual lubricant-related fuel economy benefits.
Within the range of variables included in this study, reducing engine oil viscosity is the most effective way to improve fuel economy. Fuel savings realized from friction-reducing additives are relatively modest and many of the more effective materials are shown to have poor performance in standard sequence tests, particularly regarding engine wear. The most appropriate fuel-saving engine oil should combine the benefits of low viscosity along with the use of a carefully selected and thoroughly tested friction-reducing additive.
We strongly support industry efforts to standardize a test procedure for identifying fuel-saving engine oils. Based upon these studies and other investigations, the most suitable method for such a procedure are the EPA FTP and HWFET cycles.