Table of Contents

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Corrective maintenance of car engines requires effective service for worn-out parts and choosing the right motor oil for lubricating the engine’s moving parts.
Car vacuum cleaners come in many designs and forms, the most common of which is the handheld car vacuum. Top 15 Best Car Vacuum Cleaners in 2018 cleaner.

Many car owners may drop their cars at the mechanic shop for an oil change. However, as the car owner, you should be responsible for ensuring the right grade and quality motor oil for your car engine. While 5w30 and 5w40 are two popular grade motor oils, many people need to learn the difference between them. Continue reading the article to explore a comparison between these two.

Short on Time – Here’s a Quick Summary!

5w30 and 5w40 are multigrade motor oils with the same low-temperature viscosity, i.e., 5, as the number preceding “W” indicates winter viscosity. However, both have different viscosity at operating temperatures. For example, 5w30 has “30”, and 5w40 has “40” high-temperature viscosity.

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Viscosity and Engine Oil Viscosity Grade

Before we compare 5w30 and 5w40 oils, it is necessary to understand viscosity and how motor oils are graded.

  • Viscosity: The viscosity of an engine oil refers to its thickness and resistance to flow.

 

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Thinner engine oil flows more efficiently than thicker engine oil. Since oil’s thickness changes with temperature, engine oil is thicker when it’s cold and thinner when it’s hot.
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Engine Oil Viscosity Grade

The Society of Automotive Engineers (SAE) defines viscosity grading based on oil characteristics and the oil’s ability to flow at low and high temperatures.

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While looking at a multigrade oil, you may see two numbers and the letter W. For instance, 5w30 grade motor oil. Here is what it means.

  • The number preceding W indicates the oil’s low-temperature viscosity.
  • The “W” stands for winter.
  • The number after the letter indicates the oil’s high-temperature viscosity.

 

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Car vacuum cleaners come in many designs and forms, the most common of which is the handheld car vacuum. Top 15 Best Car Vacuum Cleaners in 2018 cleaner.
Single-grade motor oils also exist with only one viscosity grading number. For instance, SAE 20 oil. However, such oils have a narrow viscosity range and are unsuitable for modern automotive applications.

Comparison Between 5w30 & 5w40 Motor Oil

This section will discuss the similarities and differences between 5w30 & 5w40 grade motor oils. But first, let’s have a look at their similarities.

Similarities

5w30 and 5w40 have the following similarities between them.

  • Cold Weather Viscosity: Both 5w30 and 5w40 have the same low-temperature viscosity indicated by the number preceding W, which is the same for both motor oil.
  • Performance: Since 5w30 and 5w40 have the same cold weather viscosity, they will perform identically in colder climates.
  • Temperature Range: Due to identical cold weather viscosity, the temperature range of 5w30 and 5w40 is the same for colder weather, which starts from -30°C for both motor oils.
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Differences

Here are some key differences between 5w30 and 5w40 that will help you decide which one might be better for your car engine.

  • 5w30 vs. 5w40 Viscosity

Viscosity is a critical factor when choosing engine oil. It helps decide which engine oil is better for your car. The working viscosity for 5w30 ranges from 9.3 to 12.5mm2/. On the other hand, the operating viscosity for 5w40 is 12.5 to 16.3mm2/s. These numbers show that 5w30 has a lower viscosity than 5w40, making it better than the latter. However, 5w40 will outperform 5w30 in higher temperatures.

  • 5w30 vs. 5w40 Grade

There are eleven motor oil grades, as suggested by the SAE grading system. They begin from 0w to 25w for cold operation and 20 to 60 for hot temperatures.

While 5w30 and 5w40 have the same grade for low-temperature viscosity, they are on a different level when exposed to hot surroundings. Both will withstand cold temperatures due to their low viscosity. However, 5w40 will bring its best in hot climates compared to 5w30.

  • 5w30 vs. 5w40 Performance

The next comparison between 5w30 and 5w40 engine oil is for their performance. As mentioned earlier, both engine oils will perform identically in colder climates due to their same low-temperature viscosity grade.

While discussing the higher side, these two lubricants perform differently at higher temperatures. Since 5w40 has higher high-temperature viscosity, which is “40”, it will perform better in a hot climate than 5w30.

  • 5w30 vs. 5w40 Fuel Economy

Fuel economy is generally measured by the distance traveled by a vehicle on a given fuel volume. Therefore, the better a vehicle’s fuel economy, the farther it can travel on a gas tank. Also, fuel-efficient vehicles emit less pollution while traveling the same distance.

If we compare the 5w30 and 5w40 in fuel economy, the 5w30 has proved more fuel economical than the 5w40. The thicker the oil, the more energy the engine will consume to pump that oil, increasing fuel consumption. Since 5w40 is thicker than 5w30, it will consume more fuel than 5w30.

  • 5w30 vs. 5w40 Pricing

The next attribute to compare is the price of these two engine oils; 5w30 and 5w40. While price is the deciding factor when buying different engine lubricants, the cost of 5w30 and 5w40 varies a little and depends on the lubricant brand you might choose. For instance, the difference between Mobil1 5w30 and 5w40 is a little. However, 5w30 is usually cheaper than 5w40 grade engine oil.

  • 5w30 vs. 5w40 Temperature Range

While the low-temperature range is identical for 5w30 and 5w40, they vary in terms of higher temperatures. For example, 5w30 can be used in temperatures ranging from -30°C to 30°C. On the other hand, 5w40 can be used in temperatures ranging from -30°C to 35C.

  • 5w30 vs. 5w40 Application 

Applications for 5w30 and 5w40 engine oil are different. Manufacturers suggest using 5w40 grade engines, usually for most diesel engines. Rarely do they recommend using 5w40 oil in a gasoline engine. On the other hand, it is recommended to use 5w30 oil for many modern gasoline applications.

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The table below shows a comparison of the 5w30 and 5w40 grade motor oil at a glance.

5W30 Motor Oil5w40 Motor Oil
Low-temperature viscosity is 5.Low-temperature viscosity is 5.
High-temperature viscosity is 30.High-temperature viscosity is 40.
Better fuel economy than 5w30.Inferior fuel economy than 5w30.
They are mostly used in passenger cars, SUVs, light vans, and gasoline engines.They are mostly used in diesel engines.
Performs well in winter as well as summer.Performs well in winter and better in summers compared to 5w30.
5w30 can be used in temperatures ranging from -30°C to 30°C.5w40 can be used in temperatures ranging from -30°C to 35C.

Takeaway

The comparison between the 5w30 and 5w40 shows significant differences between the two motor oils. While both have the same low-temperature viscosity, 5w30 and 5w40 have different high-temperature viscosity, which are 30 and 40, respectively.

Also, 5w40 will be thicker in the operating temperature of the engine and protect the engine better in an extremely hot climate. Therefore, you can choose 5w40 grade oil if you live in a hotter area. However, if you live in a colder climate, it doesn’t matter which oil you use among them since they both have the same low-temperature viscosity, which is 5.

FAQs

While both 5w30 and 5w40 have the same viscosity grade for cold climates, 5w40 is thicker than 5w30 in hot climates. So, if you live in an area where it is usually hot, consider choosing 5w40. However, if you live in a cooler area, it doesn’t matter which oil you use between 5w30 and 5w40 since both have the same low-temp viscosity.

5w40 is a good option for starting your engine in cool weather since it has good low-temperature viscosity. However, 5w40 will be equally effective when the engine reaches its operating temperature, as it has good high-temp viscosity. Also, it will protect against engine wear.

5w30 is a multigrade oil, and its viscosity range means it can lubricate and protect the engine’s internal parts in various climates. This makes it a good option for summer as well as winter. However, 5w40 will perform better than 5w30 in summer.

While it is not recommended to mix different oils, you can mix 5w30 and 5w40 if you’re low on engine oil. Also, if you live in a cooler climatic condition, mixing them will not affect much since they both have the same low-temp viscosity. However, ideally, it is not suggested to mix different oils.

5w40 grade motor oils are well suited for various climatic conditions and are effective for engine startups in temperatures as low as -30°C. Also, they are an ideal recommendation for American diesel pickup truck engines.

About Author

Andrew Ray

Andrew is an automotive technician with 10 years of experience mainly in American and Japanese cars, covering everything from routine vehicle maintenance and engine inspections to tire rotation.