Oil is kinda of my thing.
The math you did, doesn't work, though, with oil and viscosity. There are tools on the web, one being the Widman Viscosity Calculator, that pretty accurately gets you the cold and hot points for viscosity of fluid blends. I actually simply thickened the hot point of the 40 weight to the top of the API 40 weight viscosity scale. I don't care about the cold side, the garage has never been below 40 degrees, and we are moving into warm weather rapidly. But I want, for me, and me alone, your mileage may vary, the thickest oil in the sump I can get, and still stay in the spirit of what CanAm is calling for. .......