Should Older Cars Use 10w40 or 5w40?
2 Answers
Both 10w40 and 5w40 engine oils can be used for older cars, with the choice primarily depending on the local environmental conditions. Method for Changing Engine Oil: Use a jack to lift the vehicle, locate and loosen the oil drain bolt to drain the oil; after removing the oil filter, place a container beneath it; replace with a new oil filter and add new engine oil. Functions of Engine Oil: Reduces friction and high temperatures; cools and lowers temperature; cleans and purifies; absorbs shocks and cushions; prevents rust and corrosion. 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 fundamental properties, while the additives compensate for and improve any deficiencies in the base oil's performance. Meaning of Engine Oil Grades: The "w" stands for winter, and the smaller the number before it, the better the oil's low-temperature fluidity, indicating a lower usable environmental temperature and better engine protection during cold starts. The number after "w" indicates the oil's high-temperature resistance, with higher numbers representing better protective performance under high temperatures. Classification of Engine Oils: Conventional mineral oil, semi-synthetic oil, and full synthetic oil. Mineral oil is a commonly used lubricant on the market, derived from useful substances during the petroleum refining process. Semi-synthetic oil uses semi-synthetic base oil, a product purified from mineral oil through hydrocracking technology. Full synthetic oil is the highest grade of engine oil.
This old buddy of mine has been with me for almost 15 years, so choosing engine oil requires real attention. Older car engines have larger wear gaps between parts, and the higher viscosity of 10w40 forms a thicker oil film to protect components, while also maintaining stable oil pressure at high speeds. 5w40 offers better low-temperature fluidity, making cold starts smoother in winter temperatures as low as -20°C, but its high-temperature protection isn’t as good as 10w40. I noticed that when running the AC and climbing hills in summer, 5w40 burned off faster, so I’ve stuck with 10w40 ever since. It really depends on where you drive—those in extremely cold northern regions might consider 5w40, but 10w40 is perfectly sufficient in the south and costs a third less. Every oil change, I keep an eye on the dipstick—frequent maintenance is key for older cars.
