A method for managing oil temperature for a vehicle engine comprises the steps of (a) determining a preferred temperature window for oil in operation of the vehicle, comprising a first, lower temperature, and a second, higher temperature; (b) pumping oil from the vehicle engine to a control valve controlling oil passage into a radiator, and bypassing the radiator via a by-pass passage in the control valve more than seventy-percent of the oil to return to the vehicle engine without passing through the radiator upon cold start-up; (c) closing the bypass passage at the first oil temperature, forcing all oil entering the control valve to pass through he radiator before returning to the vehicle engine; (d) starting a forced-air fan at the second temperature to urge ambient air through air passages of the radiator, thereby enhancing ability of the radiator to cool the oil passing through.