Lubricants With Calcium-Containing Detergents and Their Use for Improving Low-Speed Pre-Ignition

A lubricating oil composition comprising:

• greater than 50 wt. % of a base oil of lubricating viscosity, based on a total weight of the lubricating oil composition;
• one or more overbased calcium sulfonate detergent(s) having a total base number of greater than 225 mg KOH/g, measured by the method of ASTM D-2896, and
• one or more overbased calcium phenate detergent(s) having a total base number of greater than 170 mg KOH/g, measured by the method of ASTM D-2896,
• wherein a ratio of the ppm of calcium in the lubricating oil composition from the one or more overbased calcium sulfonate detergent(s) to the ppm of calcium in the lubricating oil composition from the one or more overbased calcium phenate detergent(s) is greater than 1.20 to less than about 1.51,
• a ratio of total ppm of nitrogen in the lubricating oil composition to total wt. % of soap from the detergents in the lubricating oil composition is greater than about 2080, and
• a total base number contribution from all detergents is less than 4.2 mg KOH/g of the lubricating oil composition, as measured by the method of ASTM D-2896.