Dynamic Viscosity at -30c

[compression]

Hi

What do these two figures for dynamic viscosity at - 30°C mean?

Castrol Edge 5w40 Viscosity, CCS -30°C (5W) ASTM D5293 mPa.s (cP) 6220
Fuchs Titan GT1 5W-40 Dynamic Viscosity at - 30°C DIN 51398 5700 mPas

Thanks

Sources
http://www.generaloils.net/PI_TITAN-GT1-5W-40_e.pdf
http://www.opieoils.co.uk/pdfs/castrol/castrol-edge-5w-40-fst.pdf

 

[weasley]

CCS stands for "cold cranking simulator". This test is one of the ones used to determine the SAE viscosity rating. For an oil with a 5W rating, the CCS test is carried out at -30°C.

The results you show there show that under the same conditions, the Fuchs oil has a lower viscosity than the Castrol one. Both results fall below the maximum limit allowed for 5W, which is 6,600 mPa.s. mPa.s are the units used to express this type of viscosity; it is also referred to as cP (centipoise).

The DIN and ASTM numbers are references to the test methods employed - DIN is essentially a German test method and ASTM is American; in this case the two methods are unified and are the same.

The CCS test replicates the conditions in a crankshaft bearing with a cold start. The test involves placing a rotor in a cup with a very small gap around it. The oil fills the gap, is cooled to the test temperature than the rotor is turned. The torque needed to turn the rotor at a certain speed tells you the resistance that the oil is offering, which is its viscosity.

 

[compression]

Great, thanks for the reply.