0w40 vs. 5w40 : What are the Differences?

Engine oil is like the blood of an engine, playing the crucial role of lubrication. It is a must-have, considering that the car engine has several moving components. Did you know that there are different engine oils? In this article, we look at engine oils suitable for winter conditions. The discussion on 0w40 and 5w40 will tell you the two oils are both synthetic, though, in some oil brands, you may find the 5w40 to be a synthetic blend. Synthetic engine oils are a to-go option for many due to their attributes like cleanliness and consistency, making them efficient lubricants.

Below is more about 0w40 vs. 5w40 to give you a better understanding of their functionality.

0w40 vs. 5w40

Comparison table between 0W-40 and 5W-40

The primary difference between 0W-40 and 5W-40 engine oils lies in their viscosity ratings. Here’s a comparison table between 0W-40 and 5W-40 oils to give you a precise and quick outlook of both engine oils:

Characteristics 0W-40 Engine Oil 0W-50 Engine Oil
Cold Temperature Performance Excellent cold flow properties, better for extreme cold start-ups Slightly less fluid at very low temperatures compared to 0W-40
Viscosity at Operating Temp Thicker at high temperatures, suitable for demanding conditions Slightly thinner at high temperatures compared to 0W-40
Fuel Efficiency It may offer slightly better fuel efficiency due to lower viscosity at lower temperatures A slightly higher viscosity may marginally reduce fuel efficiency
Temperature Stability Offers excellent stability at high temperatures Very good stability at high temperatures, although slightly less compared to 0W-40
Wide Temperature Range Suitable for a wide temperature range, from extreme cold to high heat conditions Effective over a broad temperature range, but slightly less ideal for very cold conditions compared to 0W-40
Engine Wear Protection Very good Excellent

0w40 vs. 5w40 Explained

To understand these two oils, you have to know their differences. A variation you may notice is in their naming, an excellent starting point for this discussion. The letter W stands for winter, giving you a hint that the two oils are ideal for cold conditions.

The first number before the W indicates the lubricant’s viscosity under low temperatures. The last number is the oil’s thickness in operating temperatures. You can see that both the 0w40 and 5w40 have a similar consistency in operating temperature.

The main contrast comes in their low-temperature viscous levels. The naming is in accordance with the SAE grade. While both are great for operating in low-temperature conditions, the 0w40 is the perfect choice for extreme temperatures. Its low viscosity means it will flow fine and bring its best to lubricate the engine’s moving parts.

Getting more profound to the discussion, we can look at the 5w30 vs. 5w40 vs. 0w40 debate. In this situation, we bring in another variety, the 5w30. It has the same low-temperature thickness as the 5w40 and a lower high-temperature viscous value.

The 5w40 and 0w40 have an edge above the 5w30, especially in moderate to high heat. In hot conditions, the engine performs well if the oil is thick.  What of 0w40 vs. 10w40? 10w40 is fit for mild weather, more like the summer conditions that you will find in the southern states of the United States that are pretty hot.

10w40 brings its best in relatively cold weather to manageable hot weather. The 0w40 finds extensive use in European vehicle models due to the continent’s coldness, which at times borders to the extreme.

can you mix 0w40 and 5w40

0w40 vs. 5w40 Viscosity

When looking at engine lubricants, viscosity is a critical factor. It refers to the fluids’ flow, where you may describe it as thick or thin. 0w40 vs. 5w40 viscosity factors in the temperature.

A look at the thickness attribute you see that 0w40 is the ideal option for cold temperatures. It is less thick when cold and less prone to thickening as temperatures dip. As it remains thin and flows easily, 0w40 will act against engine problems like bearing failure.

The 5w40 also has a tremendous low-temperature thickness, though slightly below its companion. For hot weather, the two oils’ viscous values are 40. They become thicker; hence, they offer more protection to the engine parts.

0w40 vs. 5w40 Grade

As per the SAE grading system, there are eleven engine oil grades. The grades begin at 0w to 25w for cold operations and 20 to 60 for hot environments. The numerical and alphabet digits give you an idea of how the lubricants will work under different circumstances.

A thing to appreciate about 0w40 and 5w40 is that they are multi-grade utilities that work in cold and hot surroundings. For high-temperature surroundings, the two grades tie at the 40-limit. At 40, their viscosity thickens, offering ample protection to the engine.

However, the two are not on the same level when exposed to cool surroundings. The 0w40 will withstand extreme cold due to its low viscosity. 5w40 will bring its best in extreme conditions, but not at the same level as its companion.  If you live in relatively cold to warmer areas, the 5w40 will serve you perfectly.

Still, on engine lubricant grades, there is the API system, which stands for the American Petroleum Institute. This system certifies that the oil you are using meets OEM standards and is according to the latest automotive technology.

The API system uses the letter S, followed by another letter to show you compatibility in terms of the vehicle’s year of manufacture. Presently, SJ, SK, SL, SM, and SN are the letters that you will encounter that are not obsolete. They are for car models manufactured in 2001 and later.

A thing to note is that SAE 0W40 is not the same as SAE 0-40. You can consult your retailer for help in case of any confusion.

0w40 vs. 5w40 Performance

The other area to look at on the 0w40 vs. 5w40 debate is their performance. Performance-wise, we pay much attention to the weather or climate. If it is cold, the engine can pump 0w40 down to around -40 degrees Celsius. On the other hand, it is possible to pump 5w40 at roughly -35 degrees Celsius. Here, 0w40 vs. 5w40 for winter, you see that the former comes on top, especially if the conditions are critical.

On the higher side, temperature-wise, the two lubricant grades will reach a value of 40, as denoted in their names. As such, when hot, they are equal in viscosity, translating to a similar performance.

What about 0w40 vs. 5w40 diesel engines? Diesel engines get hotter when running, meaning both of the oils will work well. However, the 0w40 will come in handy if the temperatures are dipping at an alarming rate.

0w40 vs. 5w40 Fuel Economy

The fact that 0w40 retains its fluidity when the cold makes it ideal for fuel economy. It provides the much-needed lubrication to ensure the engine parts don’t strain to move. The ease of movement does not require much force; as such, there is low fuel consumption.

The same applies to 5w40, despite its cold tolerance being slightly lower than that of its counterpart.

0w40 vs. 5w40 Price

Another attribute to look at is the prices of 0w40 and 5w40. The cost does not vary much and depends on the brand. For instance, if you decide to go for the Pennzoil ultra variation, you find that 0w40 and 5w40 have a dollar difference.

Some brands like Castrol, have a higher variation, though there are several types of Castrol engine oil. You have to be specific to get the right bottle of oil.


Can I Use 0w40 Instead Of 5w40?

Substituting engine oils is an issue many people have a concern about, considering that some industry pundits advise against it. In the case of 5w40 and 0w40, you can use them interchangeably as they have almost similar characteristics. For icy conditions, you can jump ship to the 0w40 as it has excellent fluidity in a freezing environment.

What Is 0w40 Oil Used For?

Ow40 oil is ideal for winter conditions, where it has 0 viscosity when temperatures dip. It is a multi-grade oil with an operating thickness of 40 when it is hot. 0w40 is pretty versatile as it will protect the engine parts when hot and flow smoothly when cold.

Is 0w Better Than 5w?

The W in most oil-grade alphanumeric systems denotes winter. In winter, where driving environments are poor due to cold, the 0w will work better than 5w as it is less dense. The thinness of the oil makes it effective in reducing friction and easing the movement of the engine parts.

Is 0w40 Good For Winter?

0w40 is a multi-grade oil that works well in winter conditions and moderate summer heat. The number 0 indicates how thick it is in winter, an ideal level for effortless flow. If the lubricant gets thick due to freezing temperatures, its performance gets affected.

Is 0w40 Good For Summer?

0w40 is very versatile when you look at its functionality. It works in winter conditions and moderate summers. It will reach a viscosity level of 40, evident in its name when hot.

Is Mobil 1 0w40 good oil?

Mobil 1 is one of the most prominent lubricant manufacturers with branches worldwide. Mobil 1 stocks the 0w40 lubricant under its rich catalog. Its product lives up to the company name and will provide excellent engine performance when temperatures depreciate.

Final Word

Your choice of car lubricant should rely on operating temperatures as one of the critical factors. If you drive in winter-like conditions, you should consider 0w40 or 5w40 engine oils. From this article, we have a clear picture of how the two work and some of their characteristics.

You may also consider looking at 0w20 or 5w20, which are almost similar to the aforementioned, albeit with a lower operating heat value.

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Hi there, I am R. Hasan Tito, a mechanic, and owner of this website. My friend and I created this website to share our knowledge, expertise, and experience with our fellow mechanics' community and car users. I am a specialist and certified automotive mechanic (Both Heavy Commercial and Private Cars). I worked as a Mechanic and Mechanic Supervisor for over fifteen years at Global Rebound Automotive companies - Toyota, TATA, BMW, Nissan, TVs, and Others. Now, I enjoy my new role of leading a team of automotive experts (in their respective fields) and publish new content on a regular basis on my website and social media.

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