The W stands for WINTER, this is commonly mistaken by many who consider this to stand for Weight. The number before the W represents the viscosity (thickness)and rates the oil’s flow at -17.8 degrees Celsius. So, a 5W-30 would thicken less than a 10W-30 but more than 0W-30. The second number after the W represents the oils viscosity measured at 100 degrees Celsius. This demonstrates the oils resistance to thinning at high temperatures.
Example – a good way to remember how oil reacts to temperature is by imagining you’re adding cooking oil in to a frying pan – at first, when the oil hasn’t had a chance to heat up it starts out quite thick but once the pan gets hotter, the oil becomes thinner and runnier.
Low temperatures = Thicker
High temperatures = Thinner
Motor Oil Grades
Take a look at some internationally used engine oil grades-
1) 0W-20 This engine oil is relatively thinner when you start the engine. Here in 0W-20, the viscosity of the oil is 0 when the motor is cold. When the engine reaches its normal operating temperature the viscosity of the oil becomes 20.
2) 0W-30 The 0W-30 oil is engineered to behave as a 0-weight oil at the starting temperature and a 30-weight oil when the engine reaches its normal operating temperature.
3) 0W-40 The 0W-40 oil is engineered to behave as a 0-weight oil at the starting temperature and a 40-weight oil when the engine will reach its normal operating temperature.
4) 5W-30 5W-30 is the most commonly available and most extensively used engine oil in the Indian market. Most of the Indian car manufacturers recommend this.
5) 5W-40 5W-40 is the fully synthetic engine oil which performs like a 5-weight engine oil when experiencing a cold start. It acts like a 40-weight oil once the engine reaches normal operating temperature.
6) 10W-40 10W-40 is the engine oil which offers a 10-weight performance in the cold starting temperature. On the other hand, it provides a 40-weight performance at the normal operating temperature of the engine.
