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Reading the technical specifications of WD40 it says that it has a quite high kinematic viscosity (i.e. very little viscous fluid) of 2.8 cST @38C. However reading through its revealed trade secret compound composition I've discovered that there are a lot of different material on the mix that could contribute potentially towards rather a non-Newtonian fluid characteristics therefore making this kinematic high value given of viscosity apparent.

Also here is an interesting article that shows how an alkane hydrocarbon when combined with water can exhibit non-Newtonian fluid dynamics: Article

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  • $\begingroup$ I've discovered that there are a lot of different material on the mix that could contribute potentially towards rather a non-Newtonian fluid characteristics Like which ones? There are no ingredients in there that could give rise to non-Newtonian behaviour. Stuff that does exhibit non-Newtonian behaviour is of much, much higher molecular weight, like oligomers or polymers. But there are non of these present... $\endgroup$
    – Gert
    Commented Aug 9, 2021 at 20:08
  • $\begingroup$ Something is off here about the 2.8 cSt figure they are giving in their data sheet. For example pure benzene at the same temperature 38C has a kinematic viscosity of only 0.592 cSt! engineeringtoolbox.com/… $\endgroup$
    – Markoul11
    Commented Aug 9, 2021 at 20:40
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    $\begingroup$ Datasheets aren't scientific docs, errors do occurr in them. WD40 is very thin (like benzene). And it clearly isn't a non-Newtonian liquid. $\endgroup$
    – Gert
    Commented Aug 9, 2021 at 20:49
  • $\begingroup$ I have updated the "composition" link of WD-40 in the question. $\endgroup$
    – Markoul11
    Commented Aug 9, 2021 at 21:09
  • $\begingroup$ "Rheological properties of a concentrated surfactant system were determined. Flow curves for a fluid composed of an alkylbenzene sulfonate, hydrocarbon, water, and cosurfactant were obtained as a function of the amount of water added to the system. All fluids were optically clear and phase stable. Compositions that can be classified as oil-external microemulsions were found to exhibit Newtonian flow behavior. Non-Newtonian flow was observed for those compositions that were in the oil-external to water-external transition region." Ctd. $\endgroup$
    – Gert
    Commented Aug 9, 2021 at 21:33

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