Will the real base oil please stand up!

[Gary Allan]

quote:

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Not always. 40 years ago it refered to the viscosity at 0F.

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You've got to rephrase that somehow. I believe that you're saying that the "W" test/standard was different then.

It was still a "W" test/standard.

30 years ago the 1/2 day lesson on oil in my Engines class, the instructor (referencing a book), told us that a mulitvisc, 10w30 for example, was a 20 weight oil ..that met the max requirements of 10 weight oil ..all the requirements of 20 weight oil ...the minimum of 30 weight oil ..and the "W" meant that it was a winter grade.

He didn't pull this out of his a$$ (or did he

) .but all that was apparently

 

[TallPaul]

I looked in a 50-year-old Audel's Automotive book and it said the 10w and 20w were tested at zero F, but the 30 wt, 40 wt, and 50 wt were tested at 130 F. Wasn't clear exactly what the book meant, but this was from before multigrades.

 

[Jimbo]

My 1948 Aircraft Power Plants textbook lists oil viscosities tested at 210F, just like today. No "W" grades, of course. They recommended using an oil that has a pour point at least 5F below the starting temperature of the engine.

Aviation grade approximates the SUS viscosity at 210F.

Aviation / SAE
65 / 30
80 / 40
100 / 50
120 / 60
140 / 70

 

[XS650]

quote:

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Originally posted by TallPaul:
I looked in a 50-year-old Audel's Automotive book and it said the 10w and 20w were tested at zero F, but the 30 wt, 40 wt, and 50 wt were tested at 130 F. Wasn't clear exactly what the book meant, but this was from before multigrades.

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From what I remember of Audels, any information in them was at least 30 years old when the book was published, and not always all that accurate.

 

[TallPaul]

quote:

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Originally posted by XS650:
From what I remember of Audels, any information in them was at least 30 years old when the book was published, and not always all that accurate.

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Maybe that's why they went out of business.