Viscosity 5W-30 Oil - Is It Correct?

[VooDoo]

Hi guys,

For a prac we did, we are given the properties of a particular oil.

Density (kg/m^3) = 876

Viscosity (Ns/m^2) = 20.0x10^(-3)

I believe it is the dynamic viscosity. Now is this viscosity correct? Or should it be 2.0x10^(-3)

 

[Astronuc]

The units are for dynamic viscosity. Is one given 5W-30?

See these numbers for a synthetic 5W-30 oil which are in kinematic viscosity:
( http://www.lubeoilsales.com/products/XLF.htm )

Kinematic Viscosity @ 100°C, cSt (ASTM D-445) 10.3
Kinematic Viscosity @ 40°C, cSt (ASTM D-445) 50.9

Convert cSt to Pa-s and compare to 20 E-3. The actual viscosity depends on temperature.

Also see - http://www.matweb.com/search/SpecificMaterial.asp?bassnum=WEXXON020 for ExxonMobil 5W-30

 

[AlephZero]

Kinematic viscosity 10.3 cSt = 10.3 E-6 m^2/s
To convert to kinematic to dynamic viscosity, multiply by the density,
Dynamic viscosity = 10.3 E-6 * 876 = 9.02 E-3 Ns/m^2 = 9.02E-3 Pa-s

If the dynamic viscosity is 45E-3 Pa-s at 40C and 9E-3 Pa-s at 100C,
the correct value for your experiment could be either 20E-3 or 200E-3 depending on the temperature.