Lubricant composition for improved fuel efficiency

Abstract

To provide a passenger vehicle engine lubricating oil composition, and a method for improving fuel economy in a passenger vehicle engine by using the lubricating oil composition.SOLUTION: There is provided a method for improving fuel economy, comprising: lubricating an engine crankcase of a passenger vehicle engine with a lubricating oil composition; and achieving a positive increase in fuel economy as measured by fuel economy. The lubricating oil composition includes: (i) a calcium-containing hydrocarbyl-substituted sulfonate compound providing about 900 ppm or more of calcium to the lubricating oil composition, in which the lubricating oil composition lacks a sulfur-free detergent; (ii) an oil-soluble molybdenum compound providing from about 500 to about 1200 ppm of molybdenum to the lubricating oil composition; (iii) an ash-contributing additive in an amount to provide a total measured sulfated ash content of about 0.8 wt.% or less; (iv) a total base number (TBN) of the lubricating oil composition of about 6.0 mg KOH / g or more; and (v) a high temperature, high shear viscosity of about 1.7 to about 2.9 cSt at 150°C.SELECTED DRAWING: None

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