Internal combustion engines have been studied to obtain better efficiency in fuel consumption and hence lower emissions of greenhouse gases. The ideal would be to achieve these goals without sacrificing performance related to the torque and power, and specially without raising the production's cost. In this context, lubricating oil and lubrication system are very important as it has a major function in reducing engine friction. This paper presents an evaluation of the influence of different lubricating oil viscosities in cold engine friction, analyzing their effects on oil temperature, coolant, fuel consumption and starter motor speed. It also proposes a method for modeling the cold friction torque with the aid of the engine control module (ECM) idle speed control algorithm, aiming calibration time and cost reduction.