Cold crank simulator

The Cannon Instmment Company produces a line of rotational viscometers, most of which are quite specialized, eg. Cold Cranking Simulators (ASTM D5293) and Mini-Rotary viscometers (ASTM D3829 and D4684) for automotive engine oils. They also have a general use instmment similar to Brookfield s basic viscometer. 

As measured in the Cold Cranking Simulator (CCS). As measured in the Mini Rotary Viscometer (MRV). 

Cold Cranking Simulator (CCS) An intermediate shear rate viscometer that predicts the ability of an oil to permit a satisfactory cranking speed to be developed in a cold engine. 

Low temperature performance. The cold crank simulation test is of vital interest to any car owner living in a cold climate. The advantage of a PAO-based formulation in the crankcase is immediate and obvious on a cold winter morning ... 

However, multigrade oils do not behave as Newtonian fluids and this is primarily due to the presence of polymeric viscosity index improvers. The result is that the viscosity of multigrade oils is generally higher at -18°C (0°F) than is predicted by extrapolation from 38°C (100°F) and 99°C (210°F) data, the extent of the deviation varying with the type and amount of viscosity index improver used. To overcome this, the SAE classification is based on a measured viscosity at -18°C (0°F) using a laboratory test apparatus known as a cold cranking simulator (ASTM D-2602). 

The cold crank simulator test, ASTM D2602/IP 383, measures the apparent viscosity of an oil sample at low temperatures and high shear rates, related to the cold starting characteristics of engine oils, which should be as low as possible. The oil sample fills the space between the rotor and the stator of an electric motor, and when the equipment has been cooled to the test temperature, the motor is started. The increased viscosity of the oil will reduce the speed of rotation of the motor and indicates the apparent viscosity of the oil. The test is comparative for different oil samples rather than an accurate prediction of the absolute performance of an oil in a specific engine. 

Cold cranking simulator The apparent low temperature viscosity of engine oils (ASTM D5293) correlates with the ease of low temperature engine cranking, measured in centipoise rather than centistokes, and the temperature is always given (e.g., CCS at -25°C = 1405 cP). 

Viscosity is a key lube oil property and is a measure of the fluidity of the oil. There are two measures of viscosity commonly used kinematic and dynamic. The kinematic viscosity is flow due to gravity and ranges from approximately 3 to 20 cSt (centistokes) for solvent neutrals and about 30-34 cSt at 100°C for Bright stock. The dynamic viscosity is flow due to applied mechanical stress and is used to measure low temperature fluidity. Brookfield viscosity for automobile transmission fluids (ATF s) at -40°C and cold cranking simulator (CCS) viscosity for engine oils at -25°C are examples of dynamic viscosity measurements. 

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