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In order to meet ever more stringent CO2 emissions targets,OEMs are developing new technology and engine designs.Turbocharged,gasoline direct injection(TGDI)engines are more efficient and produce significant power at lower engine speeds compared to naturally aspirated engines with equivalent displacement.To ensure lubricants maintain durability and cleanliness in this new hardware,performance tests designed to minimize the frequency of low speed pre-ignition(LSPI),a destructive type of abnormal combustion observed in highly boosted engines,has been introduced into the GM dexos1TM:2015 specification and will be accepted into ILSAC GF-6.Overbased detergents have been identified as key lubricant components that impact LSPI.As a consequence,detergent systems used in many commercial products will need to be modified to reduce LSPI for next generation oils.The choice of detergent chemistry designed to ensure protection against lubricant-induced LSPI may adversely affect fuel economy performance measured in the Sequence VI engine test.This paper explores the effect of increasing overbased magnesium sulfonate detergent in a finished fluid on predicted fresh oil fuel economy improvement.We further demonstrate the impact of detergent changes on fuel economy performance in the Sequence VIE engine test.Finally,the influence of formulation modifications on normalized LSPI frequency as well as predicted fuel economy performance is discussed.