Lubricating oil composition

A lubricating oil composition adapted for use in a supercharged gasoline engine, comprising:

• a lubricating oil base oil, a compound having at least one element selected from calcium and magnesium, a compound having at least one element selected from molybdenum and phosphorous, and an ashless dispersant having nitrogen;
• wherein,
• X as determined from following equation (1):
• X=([Ca]+0.5[Mg])×8−[Mo]×8−[P]×30 (1)
• wherein [Ca], [Mg], [Mo] and [P] in equation (1) respectively represent the concentrations (wt %) of calcium, magnesium, molybdenum and phosphorous in the lubricating oil composition,
• satisfies the expression X≤−1.68;
• Y as determined from following equation (2):
• Y=[Ca]+1.65[Mg]+[N] (2)
• wherein [Ca], [Mg] and [N] in equation (2) respectively represent the concentrations (wt %) of calcium, magnesium and nitrogen derived from ashless dispersant in the lubricating oil composition,
• satisfies the expression Y≥0.18;
• and,
• Z as determined from following equation (3):
• Z=[N]/([Ca]+[Mg]) (3)
• wherein [Ca], [Mg] and [N] respectively represent the concentrations (wt %) of calcium, magnesium and nitrogen derived from an ashless dispersant in the lubricating oil composition,
• further satisfies the expression 0.3≤Z≤1.5.