Which has higher viscosity between 0w30 and 5w30 engine oil?

[DanielaMarie]

0w30 and 5w30 engine oils have the same viscosity, but differ in low-temperature flow performance. Engine oil, also known as motor lubricant, serves multiple functions for the engine: lubrication and friction reduction, auxiliary cooling, sealing and leak prevention, rust and corrosion protection, as well as shock absorption. The meanings represented in engine oil grades are as follows: 1. The number before 'w' indicates the oil's low-temperature flow performance; 2. 5w means the oil can flow normally at -30 degrees Celsius; 3. 0w indicates the oil can flow normally at -35 degrees Celsius; 4. The number after 'w' represents the oil's high-temperature viscosity, with higher numbers indicating greater viscosity.

[Amara]

I often help friends with their car oil issues. Actually, the biggest difference between 0W30 and 5W30 lies in their low-temperature fluidity. The number before the W represents the low-temperature viscosity grade. 0W can maintain fluidity at -35°C, while 5W is suitable for a minimum of -30°C. When temperatures drop below -25°C, 5W30 becomes much thicker than 0W30, requiring more effort from the oil pump during cold starts. As for high-temperature viscosity—the number 30 after the W—they are exactly the same, with no difference in viscosity under normal engine operating temperatures. So strictly speaking, 5W30 has higher viscosity at low temperatures, a difference that northern car owners know best: last winter, my car with 5W30 had noticeably more difficulty starting in the morning compared to my neighbor’s car using 0W30. After switching oils, the issue was resolved. The key to choosing oil depends on local temperatures. In places like Heilongjiang, 0W30 is definitely the first choice.

[VonMichael]

Having repaired cars for over a decade, I've encountered many owners confusing engine oil viscosity grades. In the SAE viscosity classification, the number before the W indicates the low-temperature performance rating—the smaller the number, the better the low-temperature fluidity. Simply put, in winter cold starts, 0W30 is thinner than 5W30. The number 30 after the W represents the kinematic viscosity at 100°C, where their viscosities are nearly identical. Actual tests show that at -25°C, 5W30 oil has about 20% higher viscosity than 0W30, which causes a slight lubrication delay during startup. An interesting observation: older German cars using 5W30 often have louder engine noise compared to those using 0W30, simply due to that minor difference in low-temperature fluidity. For new cars, follow the manual's recommendation. For vehicles over 100,000 km, consider slightly higher viscosity oils.

[AutumnRose]

Last time at the car club meetup, we discussed this, and the comparative test data was quite revealing. The high-temperature viscosity of 0W30 and 5W30 is exactly the same, with no difference once the engine is running. The main distinction lies in low temperatures: the low-temperature dynamic viscosity of 0W30 is around 6200cP, while 5W30 exceeds 6600cP. Here's a practical example: in a garage at -10°C, 5W30 oil takes an extra two seconds to reach the camshaft. This viscosity difference is particularly noticeable in northern winters, where dashboard warning lights often come on in older cars using 5W30. However, friends in the south needn't worry at all—unless it's extremely cold, the practical difference between these two oils is minimal.

[MatthewRose]

Engine oil viscosity should match the ambient temperature. The key difference lies in the CCS (Cold Cranking Simulator) value: 0W30 maintains a viscosity of approximately 6200 mPa·s at -35°C, while 5W30 exceeds 7000 mPa·s under the same conditions. However, both oils share the same kinematic viscosity range of 9.3-12.5 mm²/s at 100°C. Here's a clever test: freeze oil samples for two hours - 5W30 will pour noticeably slower from a measuring cup than 0W30. This characteristic significantly impacts cold-start wear, making 0W grades essential for extreme cold regions. In daily driving, fuel consumption differences are minimal - my SUV running 5W30 year-round consumes only about 0.2L/100km more than a friend's vehicle using 0W30.

[LeMiles]

Handling engine oil issues requires consideration of specific scenarios. When the engine is cold, especially on winter mornings, the viscosity of 5W30 is indeed higher than that of 0W30. Specifically, at -30°C, the dynamic viscosity of 5W30 is approximately 6500cP, while 0W30 is below 6000cP. However, once the coolant temperature reaches the operating temperature of 90°C, their viscosities become identical. This difference is particularly noticeable in older vehicles: my 2009 car used to produce a slight ticking sound during the first cold start in winter when using 5W30, but the sound disappeared after switching to 0W30. However, drivers in southern regions need not worry—as long as the temperature remains above -15°C, there is virtually no difference between the two oils. The key lies in the certification standards marked on the oil cap, as using the appropriate viscosity is most important.