Walter E. Waddey

IMPROVED FUEL ECONOMY VIA ENGINE OILS

A program was implemented to develop a passenger car engine oil that improves fuel economy. The selected approach was to incorporate fuel economy performance in a premium SAE (Society of Automotive Engineers) 10W-40 oil, retaining excellent deposit and wear control as well as compatibility with emission (oxidation) catalysts. The technical basis for fuel-efficient engine oils was established, with attention paid to oil-related frictional losses in automotive engines. Friction-reducing additive technology effects were defined, general routes to lower friction engine oils were explored, engine fuel economy dynamometer tests were conducted, and fuel economy benefits of friction-reducing engine oils were determined. The fuel-efficient SAE 10W-40 passenger car engine oil was formulated with petroleum base stocks and known additives, many of which are conventionally used. The new oil retained overall performance capabilities of the premium reference oil. In a controlled fuel economy fleet test, 18 out of 19 cars showed a fuel economy improvement with the fuel-efficient oil. The average benefit was 4.6%, compared with a baseline reference oil and several other typical 10W-40 multigrade oils. In Environmental Protection Agency road simulator (dynamometer) tests, the SAE 10W-40 oil gave 5.5% better fuel economy than the reference oil. The fuel-efficient oil was formulated on the basis of friction-related technology developed over a period of several years, and it is expected that this technology may lead to oils with even higher fuel economy improvements. A fuel economy field test statistical summary is appended.