A lubricating oil composition, a method of reducing low-speed pre-ignition (LSPI) in a direct-injected spark-ignited internal combustion engine, and a use of a lubricant composition to reduce LSPI events in such an engine. Preferably, the composition comprises a detergent comprising an overbased calcium detergent having a total base number (TBN) of at least 150, wherein the lubricating oil composition has a calcium content of at least 0.08 wt. %, based on the weight of the lubricating oil composition, and wherein the lubricating oil composition has a silicon content of at least 12 ppm by weight, based on the weight of the lubricating oil composition.