Oil viscosity grades, often displayed as a combination of numbers and letters (e.g., 5W-30, 10W-40), represent a standardized system for indicating an oil’s resistance to flow at specific temperatures. The first number, followed by “W” (for Winter), signifies the oil’s viscosity at low temperatures. A lower number indicates better flow in cold conditions. The second number represents the oil’s viscosity at a standard operating temperature (100C). Higher numbers here denote a thicker oil film at high temperatures.
Understanding these viscosity grades is critical for engine performance and longevity. Selecting the appropriate oil for a given vehicle and climate ensures adequate lubrication during engine start-up, even in cold weather, while maintaining sufficient oil film thickness to protect engine components at high operating temperatures. Historically, single-grade oils were common, but multi-grade oils offer a wider range of protection across varying temperature ranges, offering improved fuel efficiency and engine wear protection.
