A new category of lubricants is now entering the marketplace. These lubricants, known as Energy-Conserving Engine Oils, have required new formulating technology and testing techniques. This paper reviews one approach taken to develop and utilize new test techniques and their application to new formulating technology, interacting effects of lubricating oil additives and their relationship to both viscometric and friction modification effects are identified. Both gasoline and diesel passenger car crankcase oil technology are covered. The utilization of bench, laboratory engine dynamometer, vehicle chassis dynamometer, and field tests including the ASTM Energy-Conserving Engine Oil procedure, are discussed along with the correlation of these procedures.