Understanding Coefficient of Viscosity for SAE 10W-30 Oil at 25°C

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Discussion Overview

The discussion revolves around understanding the coefficient of viscosity for SAE 10W-30 oil at 25°C, particularly in relation to its non-Newtonian properties and implications for various experimental contexts.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant inquires about determining the coefficient of viscosity for SAE 10W-30 oil and questions whether the presence of non-Newtonian additives affects how the oil should be treated in experiments.
  • Another participant mentions finding a chart online but expresses uncertainty about the data's source.
  • A different participant notes that viscosity is typically specified at limited temperature points, which can vary by oil grade, and provides a link to a resource for further information.
  • One participant reiterates their initial question about viscosity and elaborates on the potential impact of the oil's additives, suggesting that these may alter viscosity under pressure while facilitating pumping in engines.
  • This participant also warns that for simple lab experiments, standard approaches may suffice, but more complex experiments could require careful consideration of the oil's properties.
  • A quote from an ASTM report is shared, indicating that the rise of non-Newtonian multigrade oils has complicated the use of kinematic viscosity as a reliable measure in critical engine zones.

Areas of Agreement / Disagreement

Participants express varying levels of uncertainty regarding the treatment of SAE 10W-30 oil as non-Newtonian, and there is no consensus on the implications of this for experimental design.

Contextual Notes

Participants highlight the dependence of viscosity on specific experimental conditions and the limitations of using kinematic viscosity as a parameter for characterizing real viscosity in certain applications.

jabers
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How do I tell what the coefficient of viscosity is of SAE 10W-30 oil? It is at 25 degrees C. My book says that multigrade oils like this have a non Newtonian blending additive. This doesn't mean I have to treat the substance as non Newtonian does it?

Any help would be appreciated.
 
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Google found this chart but I don't know the source of the data..

M1vsAmsoil.jpg
 
jabers said:
How do I tell what the coefficient of viscosity is of SAE 10W-30 oil? It is at 25 degrees C. My book says that multigrade oils like this have a non Newtonian blending additive. This doesn't mean I have to treat the substance as non Newtonian does it?

Any help would be appreciated.

I suspect it depends on what experiment you have planned. Presumably the additive makes the oil thicker when under pressure in bearings etc, while at the same time makes it easy to pump around the engine.

If you are doing simple lab experiments dropping balls into oils or something then you might be ok. If you are doing something more exotic beware...

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

Quote from ASTM report on the matter: "The rapid growth of non-Newtonian multigraded oils has rendered kinematic viscosity as a nearly useless parameter for characterising "real" viscosity in critical zones of an engine.
 

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