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With 5w30 being one of the most popular engine oils available on the market, people often query what’s the difference between 5w30 vs 5w40 engine oil.

This article will provide you with all the relevant information necessary, including a full comparison.

5w30 vs 5w40 engine oil

Table of Contents

The main differences between 5W30 and 5W40 engine oil:

  • Both 5W30 and 5W40 have the same cold-temperature viscosity (5W)
  • 5W40 has a higher viscosity at operating temperatures (represented by “40”)
  • 5W40 provides better protection for high-performance or heavily-loaded engines at high temperatures
  • 5W30 is more fuel-efficient compared to 5W40
  • 5W30 is suitable for most standard engines operating in normal conditions.

What is 5w30?

One of the most common oils available on the market for cars is the 5W30. This type of engine oil can be used for a whole variety of types of vehicles and is known for working very effectively for a wide range of temperatures.

5w30 offers great versatility which makes it very popular among car owners. Although it tends to be more preferred for winter periods, it is capable of providing necessary lubrication in warmer temperatures.

Here’s an example of 5w30 engine oil readily available on Amazon:

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What is 5w40?

5w40 engine oil is not as common as 5w30 engine oil, but still boasts loads of great attributes that attract users. 5w40 engine oil is capable of providing good protection to the engine from buildup and sludge.

This, therefore, promotes the health of your engine by preventing damage from occurring. 5w40 engine oil has the ability to move to all other moving parts inside the engine, allowing it to provide an effective grease.

Here’s an example of 5w40 engine oil readily available on Amazon:

Understanding Oil Features

In case you didn’t know, we’ll break down what everything represents in the name of the engine oil. Let’s look at SAE 5w30 as the example here:

The SAE, often put before the “5W30” is an abbreviation of “Society of Automotive Engineers”, while the 5 and 30 represent oil viscosity. The greater the number meaning the higher the oil viscosity.

The W indicates “winter”, i.e. the properties of the oil at low temperatures. The main objective of engine oil is to protect the vehicle’s engine in winter when the temperatures are low.

The oil must be light enough to run the engine without any difficulties during a cold start, while also being sufficiently dense to be able to keep the engine running at the same operating temperature.

The key aim is to reduce the viscosity of the oil at low temperatures and to increase it at high so that the same oil can be used throughout the whole year. If the oil only meets summer or winter conditions then they’re labelled single or mono-grade oils.

To achieve a multi-grade oil, more seasonal properties and conventional additives need to be added to the various motor oil base additives, for instance, the SAE 5 base.

The additives in the oil will reduce viscosity in cold engine operation, while also increasing viscosity at operational temperatures. This allows the oil to be effective at a low temperature of -25°C as well as at a high temperature of 25°C.

It’s important to note that the typical characteristics that the manufacturer puts on the packaging may vary significantly from those that the oil has during intensive work on the internal combustion engine.

Hence why it is common for car dealers to conduct their own oil tests in operational conditions so that they can find over which period of time the product loses its traits.

5w30 vs 5w40: Difference Between 5w30 vs 5w40

Both these engine oils are effective and function well during colder periods, efficiently lubricating the engine. The oil moves properly through all the parts of the engine hence making it easy to rev the engine in cold weather.

Both oils are used for warmer temperatures because the thickness provides the necessary protection for the engine. The takeaway is that 5w30 oil is better suited for colder temperatures while 5w40 oil is better for warmer temperatures.

Is 5w40 thicker than fw30? Or is 5w 40 thicker than 5w 30? I’m sure by now you understand a few differences between 5w-30 and 5w-40, but let’s go other them to help those who can’t differentiate the motor oils.

Low-Shear-Rate Viscosity for 5w30 and 5w40

The working viscosity of 40 is from 12.5 to 16.3 mm2/s at 100g, while the operating viscosity of 30 is from 9.3 to 12.5 mm2/s at 100g.

Both oils are 5 grade when cold, but 5w30 is 30 grade and 5w40 40 grade when at operating temperatures.

5w40 has a higher viscosity in higher temperatures in summer than 5w30, which contributes to the uninterrupted functioning of the motor.

High-Shear Rate Viscosity

For the operational viscosity of 40, this parameter is at least 3.5 at 150g while for an operation viscosity of 30, this parameter should be at least 2.9 at 150g.

This indicator gives an idea of ​​how much the oil sustains in extreme loads to an extent.

Temperature Range for 5w30 and 5w40

5w30 is used in temperature ranges from -25°C to 25°C, while 5w40 has a slightly greater temperature range from -25°C to 35°C.

Oil Flow

5w40 provides higher pressure but less flow. This is generally due to the thickness of the oils, which we’ll discuss next. 5w30 flows are a lot easier through the engine and because of this, it is the more popular of the two, especially in colder environments when the oil itself becomes thicker.

The Thickness of 5w30 and 5w40

5W30 is the thinner of the two oils, which also results in better fuel consumption. 5w40 oil is thicker, and therefore, will find it more difficult to flow through the engine and a poorer fuel economy.



5w30 can be used by different types of vehicles and in various ranges of temperatures but is generally ideal for colder temperatures.

5w40 on the other hand is often used in higher mileage engines and they will perform the better of the two in warmer temperatures.


5w30 is typically the more expensive of the two, but this isn’t always the case, of course, it depends on the make and model of the oil along with where it’s being purchased!

Motor Oil Buying Guide & Tips

Choosing the correct motor oil will allow you to prolong the life of your vehicle’s engine. Motor oil, as you will already know, lubricates the engine parts so that they do not rub or grind against one another, leading to its eventual wear and tear.

If you were to select the wrong oil for your engine, you will likely have issues with your parts, potentially leading to a replacement, a lot sooner than you should.

Ensuring the optimal performance of your car engine isn’t just about selecting the right oil, it’s also about changing the oil at the correct times.

It’s generally advised to change the oil every 3000 to 5000 miles so that you can preserve the engine and keep it in healthy condition. Changing the oil helps to keep the engine cool.

A regular changing of the oil is essential and helps avoids the issue of having dirty oil which isn’t effective in lubricating and cooling. It’s common for dirt contaminants and particulates to become regularly trapped in the oil, hence the need to change and replace the oil regularly.

Note: If you were to use the wrong engine oil and cause the car into maintenance or repair, you will, unfortunately, void your warranty.

The importance of choosing the right engine oil for your car will decide whether or not you will need to overhaul and change your engine.

Oil viscosity is a very important consideration as it’s the ease at which the liquid flows. The viscosity and thickness of oil are closely related to one another. The thicker your motor oil, the more viscous it is.

On the contrary, the thinner the motor oil, the lower the viscosity. Both 5w30 and 5w40 motor oils have number 5 with is then followed by W, representing winter.

Both 5w30 and 5w40 motor oils have the same viscosity in winter which is fairly low. This simply indicates that the oils flow at very low temperatures but find it easy to flow through the engine.

This is good quality motor oil, as motor oils with greater viscosity like 20w, will find it very difficult to flow through the engine in low temperatures.

This will make the oil incapable of being distributed through the engine when it is cold, thereby leading to damage and wearing away of the engine.

How Weather Affects the Type of Oil

Climate and weather plays a major role in determining the type of motor oil that you use your vehicle for. The lower temperatures will generally demand a lower viscosity.

The oil flows easily through the system making certain that the engine is at peak performance. Hence, why both 5w30 and 5w40 engine oils are proper for colder temperatures unlike 10w or 20w.

However, high temperatures require a slightly higher viscosity, but it shouldn’t be too high that it affects effective flow. You do not want oil that is too thin and easily flowing, as it could have long term negative effects on your vehicle.


To summarize, 5w30 motor oil is lighter, offers more flow, has better fuel economy, and is more versatile when it comes to applications.

Though, the 5w40 temperature range is slightly greater it is not as popular as 5w30 oil. But, it is certainly effective.

FAQs (Frequently Asked Questions)

What happens if I put 5w40 instead of 5w30?

Using a 40 weight engine oil instead of 30 weight isn’t going to hurt the engine. It may, however, it may affect your oil consumption. 5w-40 could be a big jump in viscosity. You want an oil that is thin enough so that the oil doesn’t cost you power yet thick enough to protect your engine.

Is 5w30 and 5w40 the same?

5w30 and 5w40 are similar in that they both have a viscosity of 5 in W (winter)/colder environments. The difference between 5w-30 and 5w-40 is that they have a different viscosity at operating temperature, 30 and 40 respectively. This means that the 5w40 motor oil has a greater temperature range, and is also slightly thicker than the 5w30 motor oil.

Can I use 5w40 in a high mileage engine?

For the most part, high mileage engine oil contains a chemical designed to slightly swell elastomeric seals in the engine, intended to compensate for age and wear, and to forestall leaks. Your 5w40 motor oil should be okay to be used in a high mileage engine, however, it’s thickness could limit the amount of oil reaching the engine.

Please leave a comment below if you have any questions about the difference between 5W30 and 5W40!

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