Disclosed herein is a composition comprising: A) a lubricant; and B) a mixture of antioxidants, wherein said mixture is prepared by the partial condensation of an alkylated diphenylamine with an aldehyde or ketone in the presence of an acidic catalyst to yield at least one acridan of the general formula: wherein: R1, R2, R3, and R4 are independently selected from the group consisting of hydrogen, C3 to C32 alkyl, and C3 to C32 alkenyl, provided that at least one of R1, R2, R3, and R4 is not hydrogen, and R5 and R6 are independently selected from the group consisting of C1 to C20 hydrocarbyl and hydrogen; wherein, at the termination of said condensation, residual alkylated diphenylamine is not separated from the acridan product.