Consider two oils, both synthetics and both made by the same manufacturer. One is a 5w-20, the other is a 5w-30. Viscosities are 49.5 and 65.3 [email protected]°C. Viscosity indices are 156 and 161. Pumping viscosities are 22200 and 34800 [email protected]°C. All data respectively. I'd like to know how you think these oils would perform on startup. I don't understand the significance of the difference in these viscosity and pumping values for two oils both designated as 5 weight. There is an absolute value difference of about 30% in viscosity at 40°. How do you think this difference would affect the delivery of oil in a cold engine, with the assumption that the oil is used in a temperature environment appropriate for a 5 weight? Please comment on how you think these two oils would perform their lubricating function at startup. Also, would the baseline differences affect the lubrication performance as the oil and engine warmed to operating temperature? Are there significant strengths and weaknesses of each, or is the difference between the two actually neglible, based on the data values that I reported? Still learning, thanks much.