ENGINE COOLANT COMPOSITION FOR AUTOMOBILE, CONCENTRATED ENGINE COOLANT COMPOSITION FOR AUTOMOBILE AND OPERATION METHOD OF INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To provide an engine coolant composition for an automobile, which has a specific kinematic viscosity by an appropriate thickening effect of a surfactant as a viscosity characteristic improving agent, suppresses foaming property of the surfactant at high temperature, and has durability.SOLUTION: The engine coolant composition for an automobile comprises the following components: (A) a non-silicone-based surfactant; (B) a mineral oil; (C) an antifoam agent comprising silica; and (D) a base agent. The base agent (D) comprises at least one alcohol selected from the group consisting of monohydric alcohol, dihydric alcohol, trihydric alcohol and glycol monoalkyl-ether, and/or water. The coolant composition has a kinematic viscosity of 8.5 mm/sec or more at 25°C and 2.0 mm/sec or less at 100°C and contains the mineral oil (B) by 0.01 to 0.4 parts by mass and the silica (C) by 0.003 to 0.1 parts by mass with respect to 100 parts by mass of the coolant composition.SELECTED DRAWING: None