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where U is the oil's kinematic viscosity at 40 °C (104 °F), Y is the oil's kinematic viscosity at 100 °C (212 °F), and L and H are the viscosities at 40 °C for two hypothetical oils of VI 0 and 100 respectively, having the same viscosity at 100 °C as the oil whose VI we are trying to determine.
A 10W-30 oil must pass the SAE J300 viscosity grade requirements for both 10W and 30, and all limitations placed on the viscosity grades, such as the requirement that a 10W oil must fail the 5W requirements. Viscosity index improvers (VIIs) are special polymer additives added to oil, usually to improve cold weather performance in passenger ...
The grades include single grades, such as SAE 30, and also multi-grades such as SAE 15W-30. A multi-grade consists of a winter grade specifying the viscosity at cold temperatures and a non-winter grade specifying the viscosity at operating temperatures. An engine oil using a polymeric viscosity index improver (VII) must be classified as multi ...
The proportionality factor is the dynamic viscosity of the fluid, often simply referred to as the viscosity. It is denoted by the Greek letter mu ( μ ). The dynamic viscosity has the dimensions ( m a s s / l e n g t h ) / t i m e {\displaystyle \mathrm {(mass/length)/time} } , therefore resulting in the SI units and the derived units :
Viscosity index (ASTM D2270 [11]) is a measure of the extent of viscosity change with temperature; the higher the VI, the less the change. VI is calculated from viscosity measurements at 40°C and 100°C. The viscosities of paraffinic and naphthenic base oils have very different behavior with temperature change.
Consequently, if a liquid has dynamic viscosity of n centiPoise, and its density is not too different from that of water, then its kinematic viscosity is around n centiStokes. For gas, the dynamic viscosity is usually in the range of 10 to 20 microPascal-seconds, or 0.01 to 0.02 centiPoise. The density is usually on the order of 0.5 to 5 kg/m^3.
Common greases are in the range 1 through 3. Those with a NLGI No. of 000 to 1 are used in low viscosity applications. Examples include enclosed gear drives operating at low speeds and open gearing. Grades 0, 1 and 2 are used in highly loaded gearing. Grades 1 through 4 are often used in rolling contact bearings. Greases with a higher number ...
The mini-rotary viscometer is a device used to measure the pumpability of an engine oil at low temperatures. [1] [2] Engine oils must meet viscometric standards including those determined by the MRV in order to be classifiable within SAE J300 viscosity grades.