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Recent advances in the powertrain design of gasoline engines to meet environmental regulations have posed new challenges to the engine oil development. Smaller displacement engines, often with turbochargers, developed to meet higher fuel economy standards demand higher performance engine oils in conventional areas (oxidation and deposit control, fuel economy), and completely new areas (Low-Speed Pre-ignition [LSPI], turbocharger performance). Formulating engine oils which can simultaneously meet these competing demands will become more complex with increasing performance requirements. Of particular interest for upcoming engine oil development is the phenomenon of low speed pre-ignition (LSPI). LSPI is an abnormal combustion event in which lubricating oil has been observed to play a role.

The fuel economy performance of passenger car vehicles has been an area of keen focus due to recent environmental regulations. Various efforts such as the development of new engine technologies have been undertaken to improve the fuel economy performance of these vehicles. Engine oils have also been targeted to contribute to better fuel efficiency. This has been done by introducing new lubricant additive technologies and low viscosity grade oils. In the latter case, passenger car motor oils are about to enter into a new generation in which the lower viscosity grade SAE 16 has been approved and discussion has started on the specification of viscosity grades lower than SAE 16, although SAE 0W-20 viscosity grade is the lowest in the SAE J300 specification during last decade. Nevertheless, additive technology is also important, as we previously reported that simple reduction of viscosity grade is not a solution to improve fuel economy performance in the Sequence VID test.

In this study, a green process was developed to synthesize a novel molybdenum disulfide (MoS₂)-based friction modifier (FM) for improving fuel economy performance of lubricants. These new materials were synthesized using less hazardous elemental sulfur as opposed to other sulfur sources like hydrogen sulfide (H₂S) and carbon disulfide (CS₂). Using various bench and motoring friction torque tests, it was shown that friction reduction was benefited by utilizing low molecular weight organic backbone when designing molybdenum FMs. Also, it was shown that newly synthesized molybdenum-based FMs were comparable to other well-known MoS₂ precursors.

Fuel economy is one of the most essential performance requirements for Passenger Car Motor Oil because of fuel economy regulations in many countries and increasing fuel prices. The ILSAC GF-5 specification was issued on December 22, 2009 and requires better fuel economy performance based on the Sequence VID (Seq. VID) Test and higher weighted piston deposit merits based on the Sequence IIIG Test, compared to the ILSAC GF-4 specification. Fuel economy performance is affected by viscosity, friction modification and the lubricant additive chemistries. However, fuel economy engine tests under combustion mode introduce high variability into a fuel economy measurement. Screening by bench testing is complicated by the difficulty to reproduce friction conditions of all of engine parts. A motored friction torque test using an engine is one of the better solutions for fuel economy screening.