What I mean is at what temperatures does the oil exhibit characteristics of increased viscosity, and to what degree?

For instance, 10W30 is at a viscosity of 10 between what two temperatures before the polymers that make up the viscosity improvers cause the 10 to shift to a 15, or a 20, and then to 25, or 30?

And the numbers associated with aircraft oils are derived from the Mil. Spec., or Military Specification #. So, 30 weight, is actually Mil Spec. 1065, or commercial aviation # 65, while 40 weight is Mil Spec 1080, or commercial aviation # 80, 50 weight is Mil Spec 60, but commercial aviation # 100, and 60 weight is Mil Spec 1120, and commercial aviation # 120. Rememeber pilots, "proof" is never a safe thing in aviation. "12 hours from bottle to throttle" is a safe rule...

Multi viscosity oils should never be referred to as 10-weight-40. This is a misnomer carried over from single weight oils that are referred to as "30-weight", or 40-weight. 10W30 is simply, 10-30...

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Scott Longston
Northern California Wine Country...
"Turbos whistle, grapes wine..."