SAE oil refers to motor oil classified by the Society of Automotive Engineers (SAE). This classification system focuses solely on the oil's viscosity, or thickness.
Understanding SAE Oil Viscosity
The SAE system measures oil viscosity at two key temperatures:
- Low temperatures (below zero): This determines how easily the oil flows when the engine is cold. A lower number indicates better cold-temperature flow.
- High temperatures (100°C): This measures the oil's thickness when the engine is hot. A higher number signifies greater viscosity at high temperatures.
An SAE oil grade is expressed as a number followed by a letter (e.g., 10W-40).
- The number before the "W" (Winter) indicates the oil's viscosity at low temperatures. Lower numbers flow better in cold weather.
- The number after the "W" represents the oil's viscosity at high temperatures (100°C). Higher numbers indicate thicker oil at high temperatures.
For example:
- 5W-30: This oil flows readily in cold temperatures (5W) and provides adequate viscosity at operating temperatures (30). It's a common choice for many modern vehicles.
- 10W-40: This oil is thicker than 5W-30 at both low and high temperatures, often preferred for older engines or those operating in hotter climates.
In summary: SAE oil classification helps you choose the right oil for your engine based on its viscosity, ensuring proper lubrication under various operating conditions. The SAE, the acronym for the Society of Automotive Engineers, is the body responsible for this standardized system. Their classification system relies entirely on measuring oil viscosity at specific temperatures – both cold (below zero) and hot (100°C).
