In which seasons should 15w40 and 20w50 engine oils be used?
2 Answers
15w40 and 20w50 engine oils are used in summer. The number after "W" represents the viscosity index of the oil at high temperatures. The higher the number, the higher the viscosity. Higher viscosity provides better protection for the engine. Introduction to engine oil: Engine oil, also known as motor lubricant, is composed of base oil and additives. The base oil is the main component of the lubricant, determining its basic properties, while additives compensate for and improve any shortcomings in the base oil's performance. Functions of engine oil: Reduces friction and high temperatures; cools and lowers temperature; cleans and purifies; dampens vibrations; prevents rust and corrosion. Differences between 15w40 and 20w50 engine oils: Viscosity differs: The viscosity of 15w40 oil ranges between 13.5 and 16.0; the viscosity of 20w50 oil ranges between 16.5 and 20.0. Pour point differs: The pour point of 15w40 oil is around minus twenty-five degrees Celsius; the pour point of 20w50 oil is around minus nineteen degrees Celsius.
I drive in northern regions where winter temperatures can drop below minus ten degrees Celsius. Using 15w40 engine oil is most suitable because it has lower viscosity, ensuring good fluidity during cold starts, making the engine easier to ignite and reducing wear. In spring or early autumn, when temperatures are moderate, continuing with 15w40 works well. However, when summer heatwaves arrive, I switch to 20w50, as its higher viscosity provides better engine protection under high temperatures and prevents oil film thinning. Of course, regularly checking the oil condition throughout the year is crucial, and changing the oil during significant temperature fluctuations can extend engine life. Making the wrong choice, such as using 20w50 in cold seasons, may lead to increased fuel consumption or starting difficulties. Therefore, I generally use 15w40 in winter and spring, and decide whether to switch to 20w50 in summer and autumn based on actual temperatures, making driving more worry-free.
