The 10w40 motor oil and the 10w50 motor oil have the same viscosity at zero degrees. They are known to be in the same class. In operating temperature at one hundred degrees Celsius, the 10w50 motor oil will have a higher viscosity than the 10w40 motor oil. The 10w40 motor oil will also have a viscosity index of one hundred sixty, and the 10w50 Thanks. 5W-40 = thinner oil, more wear, better fuel economy, longer (synthetic) OCI 15W-40 = thicker oil, less wear, worse fuel economy, shorter (conventional) OCI Reference: John Rosenbaum, Chevron ( link ) "The Ford manual says for severe service run 5w-40." Translation: To maintain the same OCI for severe service, use a synthetic oil. Yes, you can use 15W-40 oil in your motorcycle instead of 10W-40 oil. The main difference between the two oils is their viscosity, or thickness. 15W-40 oil is thicker than 10W-40 oil, which means it will flow more slowly at cold temperatures. However, both oils will flow the same at operating temperatures. The API standard uses weight. A 20wt single weight oil will have a specified viscosity range at 100C and a much thicker specified viscosity range at 10C. A 10W-40 multi-weight oil will be a 10 wt oil that has viscosity modifiers added to it to cause it to thin less than expected, as the temperature increases. 15w40 vs. 20w40. The 15w40 has the cranking weight in the cold of 15 as the w in its name stands for winter and has an operating temperature weight of 40, so it will flow better than the 20w40. Artificial oil generally comes in a huge range of thicknesses, such as 0w40, 5w40, and so on. Sometimes there are far too many volume index improvers Vay Tiền Nhanh Chỉ Cần Cmnd.

difference between 10w and 15w oil