PURPOSE: To prepare the subject concentrate comprising a Mannich base ashless dispersant, a sulfur-containing antiwear agent, a nitrogen and phosphorus- containing antiwear agent and the like and improving performance capacities of a base oil with lubricating viscosity containing animal, vegetable, mineral and synthetic oils.

CONSTITUTION: The objective concentrate is obtained by adding components comprising a Mannich base ashless dispersant (pref., a borated one) (A), a metal- free sulfur-containing antiwear and/or extreme pressure agent (B), a metal-free phosphorus and nitrogen-containing antiwear and/or extreme pressure agent (C) and an oily amine salt of a carboxylic acid to 20 wt.% (pref. 50 wt.%) diluent oil.