What is the difference between 0W-40 and 5W-40 engine oil?
2 Answers
Both only differ in their resistance to external low temperatures: The 5W in 5W-40 engine oil represents a resistance to external low temperatures of -30°C. The 0W in 0W-40 engine oil represents a resistance to external low temperatures of -35°C. Below are detailed introductions about automotive engine oil: Overview: Engine oil, also known as engine lubricant, is referred to as Engine-oil in English. Its density is approximately 0.91×10³ (kg/m³). It serves to lubricate and reduce friction in the engine, assist in cooling, seal against leaks, prevent rust and corrosion, and provide shock absorption. Composition: Engine oil consists of two parts: base oil and additives. The base oil is the main component of the lubricant, determining its basic properties. Additives compensate for and improve the deficiencies in the base oil's performance, granting it certain new properties, making them an important part of the lubricant.
As a long-time driver in northern China, I pay special attention to motor oil selection because the difference is palpable during cold winter mornings. The 0W-40 flows significantly better than 5W-40 at low temperatures—at -15°C for instance, 0W oil circulates almost instantly, protecting the engine from cold-start wear, whereas 5W may lag by seconds, increasing wear risks. Both maintain identical 40-grade viscosity for high-temperature protection. Through repeated experience in frigid cities like Changchun or Harbin, I've noticed that using 5W-40 results in slower starts and slightly higher fuel consumption; switching to 0W-40 delivers smoother ignition and minor fuel savings. Of course, in temperate southern cities like Guangzhou or Xiamen, 5W-40 suffices at a more economical price. The key is choosing based on local climate and consulting your vehicle manual—avoid wasteful unnecessary upgrades. Regular oil condition checks ensure engine health.
