I used the Andrade correlation method/calculator to calculate the viscosity of couple of oils at 0C (32F). Refer to the links below for the calculator and Andrade correlation method. plugged in data from the following 2 oils (same brand). Nothing specific about these oils just that I currently have the 10W in the garage. both are full synthetic. Was just curious about 0W viscosity near freezing ... Data from the oil company: Oil 1 - 10W30: KV100 = 11.60 , KV40 = 71.54 Oil 2 - 0W30: KV100 = 12.18 , KV40 = 73.21 Note: Oil #2 is A3/B4 Calculated viscosity at 0C (32F) is: Oil 1 : 657.35 cSt Oil 2 : 637.60 cSt Calculated viscosity at -17.78C (0F) is: Oil 1 : 2879.79 cSt Oil 2 : 2667.69 cSt Not a huge viscosity diff between a 0W A3/B4 and a 10W30 at freezing 0C (32F). Q: is this a very accurate method to estimate or calculate the viscosity? Any other method you guys use? viscosity calculator: Viscosity calculator info from the above web site: "Calculate the viscosity at a given temperature, when the viscosity is known at two temperatures. The viscosity of a liquid as a function of temperature can be approximated with the Andrade correlation. Given two known temperature-viscosity points, the viscosity of a liquid can be calculated for a target temperature. Lubricating oil producers normally publish the viscosity of their products at two different temperatures. ... The calculator can be a useful tool for predicting viscosity at a target temperature, but keep in mind that in real world applications a theoretical viscosity value should always be verified with a viscosimeter." Additional info from petrowiki: Oil Viscosity "Andrade's method is based on the observation that the logarithm of viscosity plotted vs. reciprocal absolute temperature forms a linear relationship from somewhat above the normal boiling point to near the freezing point of the oil, as Fig. 6 shows. ..."