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0w40 vs 5w40: Everything You Need to Know!

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Hi, I'm Azim Uddin, a student who loves cars. Visit to learn about car maintenance for beginners and experts. In my studies, I found a cool connection between hosting and car care. Join me on this journey where every road has a story, and hospitality meets the thrill of cars. Explore, learn, and enjoy the ride with me!

Last Updated on May 10, 2024 by Azim Uddin

You might have often seen these numbers on the bottles of engine oils or the user manual of your motor vehicle. These are oil grades to indicate what oil you should use in the engine for the best performance and durability. But what are the similarities or differences in 0w40 vs. 5w40?

Both 0w40 and 5w40 are multigrade oils. It means each of them works like two different grades of oil. 0w40 has a lower viscosity at low temperatures compared to 5w40. But at high temperatures, both oils have the same viscosity.

You will learn everything about these oil grades to choose the best oil for your vehicle.

0w40 vs 5w40: Comparison Chart

Before I get into the details, check this quick comparison chart to know the similarities and differences between these oils.

Viscosity Index180176
Low-Temperature ViscosityLowSlightly higher than 0w40
High-Temperature ViscosityHighHigh
Low-Temperature Range-40°C or -40°F-35°C or -31°F
High-Temperature Range40°C or 212°F40°C or 212°F
Oil ConsumptionHigherLower
Fuel ConsumptionLowerHigher
Operating Viscosity3.8-16.3
Engine Wear ProtectionHigherLower
Comparison Chart

What Is 0w40 and 5w40?

Many of you might be confused about the oil grades, especially the ones that look almost similar. Take 0w40 and 5w40, for example. Let’s discuss what these grades mean.

0w40 is a multigrade engine oil. The two numbers on either side of the ‘w’ denote the viscosity in low and high temperatures. For example, 0w means this engine oil will have a viscosity similar to a 0-weight oil during winter or at cold temperatures.

5w40 motor oil

As the viscosity of the oil will be extremely low at low temperatures, the oil will flow faster. You can imagine pouring water and honey on the same sloped surface. Water will go down much faster than honey because water is less viscous. Honey has more resistance to motion between its layers.

See also  15W50 VS. 20W50: What Is The Difference Between These Two Motor Oils?

The same happens with engine oils. If you use 0w40, it will stay thinner at low temperatures. So it will flow quickly through the engine and lubricate the components faster.

When the temperature is high, the viscosity of this oil will be like a 40-weight oil. It means the oil will be much thicker than before. A thicker oil is better for lubrication and wear protection. For 5w40, the viscosity at low temperatures is slightly higher than 0w40. It means the oil will flow a bit slower than 0w40 during a cold start. But when the engine temperature rises, its viscosity will be the same as 0w40. I hope you get the point.

0w40 vs 5w40: Side-By-Side Comparison

I will discuss the characteristics of both oils in terms of how they perform in different situations. Check it out.

0w40 engine oil

Viscosity Index

0w40 is a higher index, which means it has a more stable operating range. So, this oil will work great throughout cold and hot temperatures. The operating range is from -40°F to 104°F. However the 5w40 is less stable with a lower operating range from -31°F to 95°F.

Performance at Low Temperatures

As I have already mentioned, 0w40 is less viscous at low temperatures. It has a working range of up to -40°C or -40°F. When the ambient temperature is extremely low, the less viscous oil easily flows through the engine. As a result, it can efficiently lubricate the engine components.

5w40 has a slightly higher viscosity than 0w40 at low temperatures. This oil grade is suitable for low temperatures of up to -35°C or -31°F. As you can see, this can’t withstand extreme temperatures as much as the 0w40.

See also  10W30 Vs. 5W30: Head-to-Head Comparison to Choose the Better Oil

So, it will be suitable when the ambient temperature is a bit higher. But still, 5w40 performs almost similarly to 0w40 during cold starts.

Performance at High Temperatures

After starting the engine, it reaches its operating temperature, which is often close to or higher than 100°C. At this temperature, both oil grades have the same viscosity. They will work like a 40-weight oil, which means they will be thicker.

At this point, thicker oils are more beneficial because they protect the engine components from wear. Thin oils can break down faster and produce more sludge. So, both of these oil grades are suitable for high temperatures.

Engine Performance and Protection

0w40 allows the engine to run smoother without overheating because of its low viscosity during cold starts. The faster flow of oil also prevents unnecessary wear between engine components.

But when the engine is hot, 5w40 provides better lubrication and protection. Though both oils have the same viscosity grade at high temperatures, 5w40 has a slightly higher viscosity. So, it will be more suitable for protecting high-performance engines.

Thinner oils produce more sludge or deposits that can harm the engine in the long term. 5w40 is a better engine oil in terms of engine protection because it is less prone to breaking down and producing sludge. So, you can use this engine oil for longer. It also increases the service life of the engine.

Read More: 0w40 vs 10w40: Similarities, Differences, and Use Cases

See also  20w40 Vs. 20w50: Which Motor Oil Should You Choose?

Engine Oil Consumption

If the engine oil is less viscous, it will be quickly consumed by the engine. Thinner oils also break down faster at high temperatures. So, your engine will need more 0w40 compared to the 5w40.

But as 5w40 is slightly thicker, the engine will consume less of it. It also has a longer service life than 0w40. So, it can be a more economical choice.


Fuel Consumption

When the engine oil is thinner, it flows through the engine with less heating effort. So the engine can quickly reach its normal operating temperature. It helps the engine to be more fuel-efficient.

As for 5w40, the engine will not have enough lubrication until the oil is hot. During that period, the engine will have a lower fuel efficiency. So, the choice of oil will impact your fuel cost.


0w40 is more expensive, found at $27.97, and 5w40 costs $20.22.

Which Is Better Between 0w40 and 5w40?

It depends on what car you drive, where you drive it, and some more factors. If you drive in Canada, America, or any cold European country, you need to use 0w40.

But if you live in warm climate regions where the temperature is above freezing all the time, 5w40 would be a better choice. Besides, you should check your user manual to find the suggested oil grade for your vehicle.


You might be looking for answers to the following questions.

Q: Can I use 0w40 in hot weather?

Of course. It can suit well in hot weather conditions due to its stable operating range.

Q: Is 5w40 better than 0w40 in cold temperatures?

No. 0w40 will flow more easily in cold temperatures. 5w40 is better when you are driving in warm weather.

Final Thoughts

0w40 and 5w40 are two multigrade engine oils with characteristics close to each other. Their viscosity index has a small difference, and so does their operating temperature range. This is why many people tend to interchange them without knowing the differences between 0w40 and 5w40.

I explained what each oil grade means and how they perform in different conditions. After considering all these factors, you can make more informed decisions and keep your engine in good condition. I suggest using 0w40 if you regularly drive in sub-zero weather and 5w40 if you drive in warm climates.

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