An additive for oils that is capable of imparting oils such as lubricant base oils with superior wear resistance properties or friction resistance properties, and a lubricant. An additive for oils that includes a compound represented by formula (I) is used. A and B each represents a single bond or hydrocarbylene or the like, X and Y each represents a sulfur atom or single bond, and W and Z each represents a hydrogen atom or —NR1R2 or the like, provided that W and Z are not both hydrogen atoms. R1 and R2 each represents a hydrogen atom, a hydrocarbyl or a hydrocarbylcarbonyl or the like, and n and m each represents an integer of 0 to 5.