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5w30 vs. 5w40: What's the Difference?

Edited by Aimie Carlson || By Harlon Moss || Published on February 15, 2024
5W30 and 5W40 are multi-grade oils; 5W30 has a lower viscosity at high temperatures, making it thinner under heat, while 5W40 maintains a thicker consistency at the same temperature.

Key Differences

Both 5W30 and 5W40 are multi-grade motor oils. The "5W" in both indicates their winter (W) viscosity rating, showing they perform well in cold temperatures. However, the difference lies in their operating temperature viscosities: 30 versus 40. 5W30 oil is thinner at high temperatures compared to 5W40, which affects engine lubrication and performance.
The use of 5W30 is often recommended for lighter vehicles and in colder environments due to its thinner consistency at higher temperatures. This can lead to better fuel efficiency. On the other hand, 5W40 is suited for heavier vehicles or those operating in hotter climates, as its thicker nature at high temperatures ensures better lubrication under stress.
In terms of engine protection, 5W30 provides sufficient protection for most engines, especially in mild to moderate climates. It's a common choice for everyday vehicles. Conversely, 5W40 offers enhanced protection for engines under heavy loads, high temperatures, or severe driving conditions, making it ideal for high-performance or heavily loaded engines.
The choice between 5W30 and 5W40 also depends on manufacturer recommendations. Many modern vehicles specify 5W30 for optimal performance and efficiency. However, some manufacturers, particularly of high-performance or heavy-duty engines, recommend 5W40 for its superior high-temperature stability.
In terms of availability, both oils are widely available and used globally. However, 5W30 is more commonly found in the market due to its suitability for a wide range of vehicles. 5W40, while also widely available, is more specialized and often chosen for specific engine types or performance requirements.

Comparison Chart

High-Temperature Viscosity


Ideal Usage Environment

Lighter vehicles, colder climates
Heavier vehicles, hotter climates

Fuel Efficiency

Generally better due to lower viscosity
Slightly lower compared to 5W30

Engine Protection

Adequate for most engines
Enhanced for high-performance or heavy loads

Market Availability

More common for a wide range of vehicles
More specialized for specific engine types

5w30 and 5w40 Definitions


Offers good fuel efficiency due to its lower high-temperature viscosity.
Switching to 5W30 oil improved my car's mileage.


Better suited for heavier vehicles and high-performance engines.
For my towing truck, I always choose 5W40 oil.


Suitable for mild to moderate climates.
For the mild winters here, 5W30 oil is the best choice for my vehicle.


Provides enhanced engine protection under high temperatures and heavy loads.
In my high-mileage car, 5W40 oil keeps the engine running smoothly.


A multi-grade oil with a viscosity rating of 5 in cold temperatures and 30 at operating temperatures.
I use 5W30 oil for my sedan for optimal performance in the city.


Often recommended for vehicles operating in hotter climates.
Living in a tropical climate, 5W40 oil is essential for my car.


Ideal for lighter vehicles and provides efficient engine lubrication.
My mechanic recommended 5W30 oil for my compact car.


Offers superior lubrication in severe driving conditions.
For off-roading, I rely on 5W40 oil for optimal engine protection.


Commonly recommended for a wide range of modern vehicles.
The user manual of my car specifies 5W30 oil for regular maintenance.


A multi-grade motor oil with a viscosity of 5 in cold temperatures and 40 at operating temperatures.
My SUV performs best with 5W40 oil, especially in hot weather.


Can I switch between 5W30 and 5W40?

It's possible, but always refer to your vehicle's manual and consult a mechanic.

Does 5W30 oil improve fuel efficiency?

Generally, yes, due to its lower high-temperature viscosity.

Is 5W40 better for older engines?

Often yes, as it provides better lubrication for worn engine parts.

Is 5W30 suitable for heavy-duty vehicles?

It can be used, but 5W40 might be a better choice for heavy-duty performance.

What are the main uses of 5W30 oil?

Ideal for everyday vehicles, especially in mild climates.

Which oil is better for hot climates, 5W30 or 5W40?

5W40 is often better in hot climates due to its thickness at high temperatures.

What does the '5W' in 5W30 and 5W40 signify?

It indicates the oil's viscosity in cold temperatures (winter rating).

Can I use 5W30 in a high-performance engine?

It's possible, but check your engine's manual; 5W40 might be better for high performance.

Is 5W40 oil thicker than 5W30?

Yes, 5W40 is thicker at high temperatures compared to 5W30.

Can I use 5W40 in a diesel engine?

Yes, but ensure it meets the specific requirements of your diesel engine.

Can I mix 5W30 with 5W40 oil?

It's not recommended as it can alter the intended viscosity and performance.

Which oil provides better cold start protection?

Both provide good cold start protection due to their "5W" rating.

Can 5W30 be used in all seasons?

Yes, it's suitable for use in various climatic conditions.

Does 5W40 oil last longer than 5W30?

Not necessarily; oil change intervals should follow your vehicle's guidelines.

Is 5W30 oil widely available?

Yes, it's commonly found in automotive stores globally.

Does 5W40 protect against engine wear better than 5W30?

Yes, particularly in engines operating under high stress or temperature.

Should I use 5W40 for a vehicle with high mileage?

It can be beneficial due to its thicker nature providing better lubrication.

Are there any downsides to using 5W30?

It might not provide enough protection for engines under extreme stress.

Is 5W40 oil more expensive than 5W30?

It can be, due to its specialized use in high-performance or heavy-duty engines.

Why would a manufacturer recommend 5W30 over 5W40?

It's often for optimal performance and fuel efficiency in specific engines.
About Author
Written by
Harlon Moss
Harlon is a seasoned quality moderator and accomplished content writer for Difference Wiki. An alumnus of the prestigious University of California, he earned his degree in Computer Science. Leveraging his academic background, Harlon brings a meticulous and informed perspective to his work, ensuring content accuracy and excellence.
Edited by
Aimie Carlson
Aimie Carlson, holding a master's degree in English literature, is a fervent English language enthusiast. She lends her writing talents to Difference Wiki, a prominent website that specializes in comparisons, offering readers insightful analyses that both captivate and inform.

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