Location. It is crucial to consider where you use the vehicle as both 0W20 and 5W20 motor oils fall within almost the same temperature spectrum. 0W-20 synthetic oil’s range is between -40°C to 20°C while a 5W20 (5W20 synthetic oil) is from -35°C to 20°C. Knowing these details means two things: The viscosity of hot oil is measured using different test parameters than when the oil is cold, so the numbers after the “W” don’t relate to the numbers in front of the “W”. The difference between 10W-30 and a 10W-40 is the high temperature viscosity. Obviously, a 10W-40 is thicker than a 10W-30 at high temperature. In the case of the 15w40, the viscosity grade is 15 in winter and 40 in hot weather conditions. On the other hand, in the case of the 10w30, the viscosity grade is 10 in winter and 30 in hot weather or high temperature. You must have a precise idea regarding the viscosity grade of the engine oil. .

difference between 10w and 15w oil