Not all owners service there own cars. in fact, most of us don’t even know what type of lubricant is use in there car. Most of use let the service be done by car service centers and mechanics.
But what if you want to buy yourself the oil? How do you know which oil to use for your car if you read the label? What does the “W” mean on the label?
In Short: The numbers represent the viscosity of the oil and the W stands for WINTER
Full explanation: The Society of Automotive Engineers (SAE) has established a numerical code system for grading motor oils according to their viscosity characteristics. Because yhe viscosity of oil change by the Temperature, they have develope multigrade oils for all temperature range. Thats how the “W” motor oil have developed.
In a 5W-40 for example, the number before the W describes the viscosity of the oil at low temperatures. The lower the number, the thinner the oil and the better the oil’s cold temperature/ cold start performance. The number after the W describes how thick the oil is at the engine’s normal operating temperature.
Multigrade oils Such as SAE 5W40 and 10W40 are widely used, they can be use under extremely hot or cold conditions. They are thin enough at low temperatures and tick enough to give a good performance at high temperature.