What is the difference between 5w40 and 10w40?
2 Answers
The differences between 5W-40 and 10W-40 engine oils lie in aspects such as grade and applicable temperature. The specific details are as follows: Grade aspect: 5W-40 is a synthetic oil, which must be SN grade, the highest grade; 10W-40 is an all-season oil, with a grade lower than SN and not available in SN grade. Applicable temperature aspect: The minimum applicable temperature for 5W-40 oil can reach minus 25 degrees Celsius; the minimum applicable temperature for 10W-40 oil is only minus 15 degrees Celsius. Technical aspect: 5W-40 uses synthetic technology, producing oil manufactured through chemical synthesis. Depending on different application purposes, synthetic oil can alter various components; 10W-40 is a conventional lubricant, composed of base oil and additives.
I've always used two types of engine oil, and the main difference between 5w40 and 10w40 lies in cold-weather starts. 5w40 flows better in low winter temperatures, making engine ignition quicker and smoother, especially in northern sub-zero conditions where the car won’t creak. 10w40 performs fine in mild climates, but when it gets cold, it tends to be thicker, making starts more strenuous and potentially accelerating engine wear. Both have the same high-temperature viscosity of 40, offering similar protection for a hot engine, but I noticed a slight improvement in fuel efficiency after switching to 5w40. Always check your owner’s manual for recommendations—in colder regions, prioritize 5w40 for safety and peace of mind; don’t risk major issues over minor savings.
