ASTM D6677

ASTM D6677 is a standardized method used to measure how much a motor oil's viscosity (thickness) changes when subjected to high temperatures. Specifically, it assesses the *high-temperature/high-shear* (HTHS) viscosity, which is critical for engine performance and protection under operating conditions. The test simulates real engine stresses to ensure the oil maintains proper flow characteristics, enabling engineers and consumers to select suitable oils for different engines, especially those operating under demanding conditions. This standardized assessment helps ensure consistency and reliability in motor oil performance specifications worldwide.