What is the difference between 5W30 and 10W40 engine oil?
2 Answers
5W30 and 10W40 engine oils mainly differ in: 1. Applicable temperature range: The freezing point temperature corresponding to 5W30 oil is minus thirty degrees Celsius; the freezing point temperature corresponding to 10W40 oil is minus twenty degrees Celsius. 2. Oil viscosity: The high-temperature viscosity of 5W30 oil is 30; the high-temperature viscosity of 10W40 oil is 40. The performance characteristics of engine oil include: 1. Lubricity; 2. Low-temperature operability; 3. Viscosity-temperature characteristics. Engine oil grades are categorized as: 1. AB series: Gasoline and light-duty diesel engine oils; 2. C series: Catalyst-compatible engine oils; 3. E series: Heavy-duty diesel engine oils.
I've been driving in the north for over a decade, and the biggest differences between 5W30 and 10W40 lie in cold-start performance and temperature adaptability. 5W30 has lower viscosity at low temperatures, with the '5' before the W indicating it maintains fluidity even at -30°C, making winter starts exceptionally smooth. 10W40's low-temperature performance is slightly inferior, resulting in some sluggishness during cold morning starts. The situation reverses during summer highway driving—the '40' in 10W40 denotes higher high-temperature viscosity, providing thicker oil film under prolonged high RPMs and better engine protection. My uncle's 200,000-km car stopped burning oil after switching to 10W40, whereas my new car achieves better fuel economy with 5W30. Choosing oil truly depends on local climate and vehicle condition—5W30 is ideal for northern vehicles, while 10W40 is more reliable for year-round high temperatures in the south.
