The 2011 Mitsubishi Endeavor uses SAE 5W-20 type oil and requires 4.0 liters of it. The 5W-20 denotes the viscosity of the oil. The number before the W describes how thick the oil gets in the cold. A 5W oil gets less thick than a 10W in winter.
The "W" stands for "winter" and refers to the viscosity of the oil at -17.8 degrees Celsius. In a very cold climate a 0W oil might be preferable because it won't thicken too much. The number after the W refers to the viscosity of the oil when it gets hot, at 100 degrees Celsius. The higher the number the more resistant the oil is to getting runny at higher temperatures.