Oil Viscosity Grade Numbers (e.g., the 10W and 30 in 10W-30 oil) represent the oil’s viscosity range and limits, not its actual viscosity. Since viscosity varies with temperature, the temperature must be specified for accurate readings. For example, a 30 grade oil has a kinematic viscosity of about 10 cSt at 100°C, ideal for most
Tag Archives: temperature
American engineers noticed that oil from Texas Gulf crude was much thicker at sub-zero temperatures compared to oil from Pennsylvania crude during World War II. This observation came to light when the U.S. military required large quantities of oil for use in various theaters of the war, including cold environments. Engineers and researchers discovered that
Dynamic viscosity measures a fluid’s resistance to deformation by shear or tensile stress, usually in centipoise (cP) or millipascal-second (mPa·s). It describes the internal friction in a fluid layer between moving plates, where higher friction requires more force to maintain movement. Dynamic viscosity varies with temperature, so measurements must include the temperature. Tools like the
Viscosity measures a fluid’s resistance to flow, reflecting its internal friction. High viscosity means the oil is “thicker” or “heavier,” while low viscosity means it’s “thinner” or “lighter.” For example, honey is thicker (higher viscosity) than water. Viscosity inversely relates to fluidity and changes with temperature. Hotter oil becomes thinner, reducing engine protection, while colder