Fuel economy improvement has been one of the most important challenges for the automotive industry, and the oil and additive industries. The automotive, oil, and additive industries including related organizations such as SAE, ASTM, and testing laboratories have made significant efforts to develop not only engine oil technologies but also engine oil standards over decades. The API S category and ILSAC engine oil standard are well known and widely used engine oil specifications  .The development of an engine oil standard has important roles to ensure the quality of engine oils in the market and encourage industries to improve the engine oil performance periodically. However, the progress of technology advancement can go faster than the revision of engine oil standard. An introduction of new viscosity grades, SAE 0W-16 and 5W-16 is one good example. The 16 grade was added into the SAE J300 standard that defines viscosity grades for engine oils in April 2013 . The addition of SAE 0W-16 and 5W-16 has opened up an opportunity to improve engine oil fuel economy performance further. The API Publication 1509 was revised to include SAE 0W-16 and 5W-16 in the API SN category in October 2014, but the fuel economy criteria could not be set due to a lack of sufficient data.Since the earlier introduction would deliver more benefit to the market, it was decided to run a statistically designed matrix to define the fuel economy improvement that could be delivered by SAE 0W-16 compared to SAE 0W-20 and propose it to related industries.