A fuel-efficient passenger car engine oil has been developed that showed an average of 4.6% improvement in fuel economy compared with several premium, SAE 10W-40 oils (API Engine Service Classification SE) in a road fleet test. In the combined Environmental Protection Agency city/highway testing, this oil gave 5.5% better fuel economy on average than an SE premium 10W-40 oil. The excellent overall performance of this lubricant was confirmed by ASTM Engine Sequence tests and evaluation in severe taxicab operations.
The new 10W-40 oil, which incorporates friction-reducing properties, is formulated with petroleum base stocks and known additives, many of which are conventionally used. It is expected that advances in friction-related technology developed in this work may lead to oils with even higher levels of fuel economy improvement in the future.