Quote:
Originally Posted by Patrick L.
If I remember correctly Mobil/Chevron 680 is an SAE 140 viscosity oil.
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I have attached a simple chart that allows you to convert from the 680 (which is an ISO grade) to an SAE Gear Oil number. One of the things that you will notice is that an SAE 140 oil spans a very large range of oil viscosity. Anything in that range, thinner or thicker, can be labeled SAE 140. Same with 250. The ISO grades are more narrow, so you know better what you are getting.
I think when you mix 50-50 SAE 140 gear oil and STP you are creating a thicker SAE 140 that is closer to ISO 680. I'm guessing.
You can buy today from Shell, Mobil or Chevron an oil that is similar to the old 600 W Cylinder Oil (which was a Mobil trademark, by the way -- not a viscosity) in 4 different ISO grades: 375, 460, 680 and 1000.
Here is a link to the Mobil Oil site that describes it:
https://www.mobil.com/en-us/industri...-cylinder-oils
I have not yet gone to the Benson Ford archives to look up what Ford's original spec was for this oil, so I can't suggest which of the above to use.
