Test methods to evaluate the effects of engine oil formulations on fuel economy were evaluated using a variety of experimental and commercial oils. The oils were tested in a motor driven engine which showed reduced power requirements for low viscosity oils at low temperatures and friction reducing additives at high temperatures. A single cylinder engine generator was able to show trends for improved fuel economy with friction reducing additives. Automotive engine dynamometer tests were run at several operating conditions and showed fuel economy improvements for low viscosity oils and for oils containing friction reducing additives. Data from vehicles tested on an All Weather Chassis Dynamometer provided an excellent simulation of field service. The laboratory test procedures correlated well with results obtained in the chassis dynamometer.