5W30 Vs. 10W40: What is the Difference?

Engine oil is an essential component for vehicles as it plays a crucial role in reducing friction among various engine parts. It enhances engine efficiency and productivity while preventing friction-related damage. 5w30 and 10w40 are the most commonly used engine oils.

The primary difference between 5W30 and 10W40 motor oils lies in their viscosity characteristics. This article explains the main difference between 10W40 engine oil and 5W30 engine oil.

What is 5W30 Oil?

5W30 is a popular engine oil suitable for light-duty diesel and petrol engines. It is categorized as a multi-grade oil, having a viscosity grade ranging from 5 (for low temperatures) to 30 (for high temperatures).

In the 5W-30, the “5W” indicates that this oil flows smoothly in extremely cold conditions, while “30” signifies that it flows more smoothly at high temperatures.

With a maximum recommended usage of 75,000 miles, 5W30 is particularly made to safeguard engine components and prolong the lifespan of your car.

Specifically, 5W-30 synthetic oil provides excellent engine protection and can last up to 75,000 kilometers (or 20,000 miles) before requiring an oil change. Its low boiling point and high flow rate enable easy flow even in low temperatures, ensuring proper lubrication of the engine parts.   

What is 10W40 Motor Oil?

10W40 motor oil is a synthetic motor oil that has been engineered to have a viscosity grade of 40 in higher temperatures (typically around 100 degrees Celsius) and 10 in low temperatures. Unlike some other oils that become thinner as they heat up, the viscosity of 10W-40 motor oil remains stable.

When this oil is cold, it maintains the characteristics of a 10W oil, providing effective lubrication even in chilly conditions. As it warms up, it acts like a 40W oil, ensuring proper flow and lubrication at higher temperatures.

The “10W” represents the cold viscosity of the oil, while the “40” indicates its performance in high-temperature conditions, specifically at 100°C in the engine.

A 10W-40 oil is denser and has higher surface tension compared to 30W oil at engine operating temperatures. This makes it a suitable choice for engines that generate high oil surface temperatures as it offers better resistance to thermal breakdown.

When opting for 10W40 oil, using a synthetic variant can provide smoother startup and improved flow compared to traditional hydrocarbon-based oils as the temperature rises.

Synthetic oils continue to flow better at higher temperatures while maintaining sufficient viscosity to protect crucial engine components such as bearings, crankshafts, and piston rings

In cold weather conditions, where lower temperatures prevail, a less viscous 10W30 oil may perform efficiently. Conversely, in warmer climates with higher operating temperatures, the denser 10W40 oil can be best suitable for preventing engine stress and strain.

5W30 Vs 10W40

The primary difference between 5W-30 and 10W-40 motor oils lies in their viscosity characteristics. The viscosity of 5W30 oil at low temperatures is 5, while 30 is at high temperatures. However, 10W40 oil has a viscosity of 40 at high temperatures and 10 at low temperatures.

Both 5W30 and 10W40 oils can be ideal according to your engine’s design and your prevailing local temperature. It’s important to note that the engine oil of your vehicle consists of various additives that contribute to its performance.

5W-30 oil is particularly best suitable for vehicles operating in cold climates. It has a viscosity grade optimized for cold weather conditions, ensuring smooth flow and effective lubrication even in frigid temperatures. However, 10W40 oil is best suitable for vehicles operating in hot climates.

The comparison table between 5w30 and 10w40 is given in the below table:

5W3010W40
5w30 is a thinner oil than 10w40.10w40 oil is a thicker oil than 5w30.
It improves fuel efficiency.It slightly reduces fuel efficiency.
In cold climates, the viscosity of 5w30 is 5.In cold climates, the viscosity of 10w40 is 10.
In hot climates, the viscosity of 5w30 is 30.In hot climates, the viscosity of 10w40 is 40.
It has excellent cold flowability.It has good cold flowability.
It is recommended for cold climates.It is recommended for hot climates.
5w30 is most commonly used in passenger vehicles.  10w40 oil is most commonly used in heavy-duty vehicles and older engines.
It provides better cold-start performance than 10w40.It provides greater engine protection under high temperatures than 5w30.