blend your own M1 5W40?

[TallPaul]

quote:

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Originally posted by Eiron:
... Don't get blinded by these categories. As you pointed out, they're nothing more than ranges represented by an average "group" number. There indeed is an 8.375 viscosity & a 43.25 viscosity, even if there are no "labeled" grades identifying them.

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Right. I have the chart showing the 100C cSt viscosity ranges for each SAE grade. And I realize you can approximate by averaging (and now lowering the result) the 100C viscosities of your mix, but ideally I would think you would want the base oil viscosities to average and then work back up from there. When I mixed 5w30 with 20w50 (to boost oil pressure without dumping all the 5w30) I got the 100C viscosities and just took the midpoints for the winter grade ratings. Four 5w30s and two 20w50s gave me 10w40, but since it is not arithmetic, probably it is a 10w30 that is high in the 30 range.

 

[Eiron]

quote:

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Originally posted by satterfi:
I built a Saybolt viscometer so I can blend lubricating oils for my automatic chain oiler.

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Mix equal parts of a 40 SUS oil and an 80 SUS oil.

The mixture will be a 50 SUS oil.

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You built your own?? That's cool! What type of machinery is the automatic chain oiler for? So, do you heat the oil up to 100°C to test it, or can you get accurate results measuring at lower temps?

Has your testing shown (or does the Data Handbook say) that the same conditions occur at the xW- end of blended multi-vis oils?