Oil density and viscosity a 20°C

[serbring]

Hi,

I'm performing some calculations and I need oil viscosity at 20°C. I have checked in some standards like SAE or ISO, but the lowest temperature I have found is 40°C. How may I extrapolate the viscosity a 20°C? Moreover I need a precise value of oil density, does someone know this value?

Thanks

 

[Mugambo]

Please refer to the temperature dependence of liquid viscosity on wikipedia:

http://en.wikipedia.org/wiki/Temperature_dependence_of_liquid_viscosity

Plug in the already available data (40°C) to extrapolate required data (20°C)

 

[serbring]

Please refer to the temperature dependence of liquid viscosity on wikipedia:

http://en.wikipedia.org/wiki/Temperature_dependence_of_liquid_viscosity

Plug in the already available data (40°C) to extrapolate required data (20°C)

thanks for the posted link, however where can I get the formula parameters?

There an ISO standard for each ISO oil type?

 

[AlephZero]

The commonly referenced SAE standards are not meant to give "exact values". They are a way to label oils so that a particular brand of oil is known to be suitable for a particular application.

The viscosity changes over the working life of an oil as its chemical composition degrades and it dissolves contaminants from its environment, so the practical requirement is to stay within a RANGE of viscosities for a minimum amount of time (before the oil is changed), not to have an "exact" value of viscosity.

Oil densities can vary widely depending on the type of oil and the additives it contains.

If you want "exact" values for a particular brand of commercially available oil, the best source of information would be the manufacturer's technical services department.

 

[serbring]

The commonly referenced SAE standards are not meant to give "exact values". They are a way to label oils so that a particular brand of oil is known to be suitable for a particular application.

The viscosity changes over the working life of an oil as its chemical composition degrades and it dissolves contaminants from its environment, so the practical requirement is to stay within a RANGE of viscosities for a minimum amount of time (before the oil is changed), not to have an "exact" value of viscosity.

Oil densities can vary widely depending on the type of oil and the additives it contains.

If you want "exact" values for a particular brand of commercially available oil, the best source of information would be the manufacturer's technical services department.

So, do I have to ask to oil supplier for getting the formula coefficients? I believed in oil classification standards there are formula coefficients too. I haven't the standard, and so before to buy it I want to understan if it is really useful for my application.
Thanks