Key Takeaways

  • The 0w40 and 5w40 match up in almost all areas
  • The 0w40 and 5w40 are both great oils for areas where the summers are hot and the winters are cold
  • 0w40 is the better choice for areas that experience extremely cold winters
  • 5w40 is the better choice for areas that experience milder winters

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The 0w40 and 5w40 are both great options for both hot and cold climates. But how do they compare? This 0w40 vs. 5w40 comparison guide has the answers.

The main difference between them is that 0w40 has a higher low-temperature resistance, compared to 5w40. In light of this, 0w40 will be more suitable for colder weather while the 5w40 engine oil will be more suited to hot weather.

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Table of Contents


Engine oil is one of your vehicle’s most essential fluids. It forms a protective oil layer between the hundreds of moving parts in your vehicle’s engine. And by doing so, it will lubricate these parts, thus helping to prevent them from grinding, and overheating – which can cause damage or even complete engine failure.

Apart from helping to lubricate your engine, engine oil also plays an important role when it comes to keeping your engine clean. Whenever your engine is running, some elements like carbon particles, acids, and resins will be formed, as a by-product of combustion. Eventually, these particles will collect in the engine oil, thus helping to prevent engine clogging.

But at some point, you will need to replace your vehicle’s engine oil. To this end, you need to ensure you choose the best oil, which will deliver the best performance for your engine.

And, the 0w40 and 5w40 are currently two of the most popular engine oils on the market. However, these two oils look almost similar. Also, they are comparable in several areas. So, distinguishing one from the other can be a challenge for most people. Fortunately, we’ve done the heavy lifting for you. In this guide, we will walk you through the key differences between the 0w40 and 5w40.

0w40 and 5w40 Differences

As we’ve mentioned above, the 0w40 and 5w40 engine oils are identical in most areas. However, as much as they perform similar duties and they are comparable in several areas, they have some slight differences.

And, it’s important to know these differences, so that you can choose the oil that aligns best with your vehicle. In this section, we will take a closer look at some of the differences between the 0w40 and 5w40 engine oils.

Temperature Rating and Viscosity

Before we dive deeper into the differences between these two engine oils, we will first walk you through some basics to give you a better understanding. First, we will begin with the letter W and the last number in both their names.

The letter W refers to the oil’s low-temperature rating. The lower the value of the W in the oil, the lower the temperatures the oil will be able to withstand without becoming overly viscous for optimal operation. In light of this, the 0w40 will remain sufficiently viscous and maintain optimal flow at colder temperatures, compared to the 5w40 oil.

The last number in both oils refers to their high-temperature rating. The higher the number in the motor oil’s name, the higher the temperature it can comfortably tolerate without becoming overly watery for optimal lubrication. In this case, both oils have the same higher temperature rating.


Another comparison area for the 0w40 vs. 5w40 is the performance. Again, we will pay attention to the climate or weather conditions. If you are using the 0w40 in cold conditions, then your vehicle’s engine will pump it down to approximately -400 Celsius.

Conversely, if you are using 5w40 in cold conditions, then your vehicle will pump it down to around -350 Celsius. As you can see, the 0w40 has an edge over the 5w40 in colder environments and climates.

In warmer temperatures, these two oils will hit a maximum value of 40, which is indicated in their names. Consequently, their viscosity levels are at par in summer conditions or higher temperatures. And, this also translates to similar levels of performance at higher temperatures.

You may be probably wondering how these two oils compare when it comes to diesel engines. Studies show that diesel engines get hotter during operation, compared to their gasoline counterparts. And, this can be attributed to various factors such as diesel’s higher viscosity than petrol. But, since these two oils have a higher temperature rating, both will work efficiently in diesel engines.

Fuel Efficiency

We are always looking for ways to save money on gas. So, which of these 0w40 vs. 5w40 two oils will save you money at the gas pump? First, we should mention that low viscosity translates to fuel savings. The reason behind this is that thinner engine oil will exert lesser strain on various components of the engine, compared to a thicker oil.

Again, we will go back to the temperature rating. As we earlier mentioned, the 0w40 will be thinner at lower temperatures, compared to 5w40. So, does this translate to fuel savings? Well, the reality is, the fuel savings for the 0w40 vs. 5w40 are negligible in a real-world situation.

The reason why you won’t observe any real-world fuel savings between these two oils is that your vehicle’s engine will heat up quite fast. From there, it will remain hot as long as it is operational. So, the time when the engine oil is cold is extremely short for you to notice any major differences. Simply put, there isn’t much difference in fuel savings when you compare the 0w40 vs. 5w40.

Price Differences

So, how do these two engine oils compare when it comes to price? The prices of various types of engine oils vary from one brand to the next. They also vary from one manufacturer to the other. For instance, Castrol, Chevron, Spec Oil, Premium Oils Valvoline and Pennzoil will set different prices for their 5w40 and 0w40 engine oils. Therefore, you can expect to find different prices from one company to the next.

But on average, the prices for the 0w40 and 5w40 range between $20 and $28 for most brands. If you were to compare prices from a single brand, you may notice the difference is around one dollar.

So, there isn’t such a big price difference between these two oils. However, you can expect to spend more on whichever oil you choose, if you decide to go for full synthetic oil as opposed to conventional engine oil. The most important thing is to ensure you purchase your oil from a reputable dealer so that you can get high-quality 0w40 or 5w40 engine oil, which will serve your engine well.

0w40 vs. 5w40: Which Oil Should You Buy?

Based on our comparisons, these two oils match up in almost all areas. Furthermore, both are great options for areas that experience hot summers and cold winters. Having said that, if your area experiences extremely cold winters, then the 0w40 comes across as the better option. As we earlier mentioned, it has a higher low-temperature resistance, compared to the 5w40.

Conversely, if your area experiences milder winters, then it will be advisable to opt for 5w40. As much as the 0w40 may still work well in areas that experience mild winters, it will be thinner at your engine’s startup compared to the 5w40. And, this translates to insufficient engine protection if you use it in such conditions.

Top Rated 0w40 and 5w40 Recommendations

By now, you have adequate information to decide which oil between the 0w40 and 5w40 you should purchase for your vehicle. But, with so many options on the market, you may be wondering which brand or type to choose. Well, we’ve simplified things for you.

For 0w40, the top recommendations are Castrol EDGE Advanced, Mobil 1 Advanced, and Liqui Moly Synthoil. And if you are looking to buy a 5w40, some of the best options on the market include Shell Rotella T6, Liqui Moly Molygen, and Valvoline Vehicle full synthetic. Regardless of the one you choose, you can never go wrong with any of these recommendations.

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About The Author

Charles Redding

Charles Redding

I've spent many years selling cars, working with auto detailers, mechanics, dealership service teams, quoting and researching car insurance, modding my own cars, and much more.

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