The alphanumeric codes found on lubricant containers, typically expressed as “XW-YY,” represent a standardized viscosity grade. This grade indicates the oil’s resistance to flow at specific temperatures. The “XW” portion denotes the oil’s cold-weather performance, with lower numbers indicating better flow at lower temperatures. The “YY” number signifies the oil’s viscosity at a high operating temperature, generally 100 degrees Celsius. For example, a 5W-30 oil exhibits the flow characteristics of a SAE 5W oil in cold temperatures and a SAE 30 oil at higher operating temperatures.
Understanding these viscosity grades is crucial for maintaining optimal engine performance and longevity. Using the appropriate viscosity grade, as specified by the vehicle manufacturer, ensures adequate lubrication of engine components across a range of operating conditions. Incorrect viscosity can lead to increased engine wear, reduced fuel efficiency, and potential engine damage. The Society of Automotive Engineers (SAE) established this system to provide a clear and consistent method for classifying oil viscosity, enabling consumers and technicians to select the correct product for specific applications.