To know the type of oil to put in your car, refer to the owner's manual. The manual contains various oil viscosities and specific temperature conditions when such viscosities are ideal. An ideal oil should also be certified by American Petroleum Institute. If possible, use synthetic oils in extreme temperatures.
Oil viscosity refers to the thickness of the engine oil. Every car engine uses a specific oil viscosity. The viscosities are represented by oil designations such as 10W-30, 5W-30, 5W-40, 5W-20 and 0W-30. For instance, in 10W-30, the number before W, 10, represents the viscosity of the oil when cold. This means that the thinness of 10 weight is more than the thinness of 30 weight, hence the oil is suitable when cold because it facilitates engine start-up and does not stress the engine.
On the other hand, the figure in front of the hyphen, 30, represents the viscosity of the oil when warm. This viscosity is ideal when the temperatures are high.
Extremely high or low temperatures disintegrate natural oils faster than usual due to the irremovable impurities contained in these oils. As a result, synthetic oils work better in extreme temperatures because they resist breakdown. However, synthetic oils are usually characterized by higher costs.