10w30 vs. 5w40 — What's the Difference?
By Tayyaba Rehman — Published on January 25, 2024
10w30 and 5w40 are motor oils with different viscosity ratings; 10w30 is thinner at low temperatures than 5w40, but both have similar viscosity at higher temperatures.
Difference Between 10w30 and 5w40
Table of Contents
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Key Differences
10w30 and 5w40 are both multi-grade motor oils, indicated by their respective viscosity ratings. The number before the "w" (which stands for winter) represents the oil's viscosity at low temperatures, while the number after indicates viscosity at high temperatures. 10w30 oil is thicker than 5w40 at colder temperatures, meaning it flows slower in low-temperature conditions.
10w30 oil is commonly used in vehicles that operate in a moderate temperature range. It provides sufficient lubrication at start-up and effective protection at higher operating temperatures. Conversely, 5w40 oil, with its lower winter viscosity, is better suited for colder climates as it allows for easier engine cranking and starting by flowing more quickly than 10w30.
Both oils reach a similar viscosity at higher operating temperatures (the "30" and "40" ratings), but 5w40 maintains a thicker consistency under heat and stress, which can be advantageous for engines operating under severe conditions. 10w30, being slightly thinner at these temperatures, can be more fuel-efficient under normal driving conditions.
10w30 oil is often recommended for older vehicles or engines with higher mileage, as its thicker cold viscosity can provide better sealing and lubrication in engines where internal wear is more significant. 5w40 is generally preferred in newer, high-performance engines, especially those requiring a higher viscosity oil for optimal protection.
The choice between 10w30 and 5w40 often depends on the vehicle manufacturer's recommendation, the ambient temperature of the operation area, and the specific conditions under which the vehicle is used. It's crucial to choose the oil that best aligns with your engine's requirements and operating conditions.
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Comparison Chart
Low-Temperature Viscosity
Thicker
Thinner
High-Temperature Viscosity
Slightly thinner
Thicker
Best Used In
Moderate climates, older or high-mileage vehicles
Colder climates, newer or high-performance engines
Fuel Efficiency
Generally more fuel-efficient
Slightly less fuel-efficient
Engine Protection
Adequate for normal driving
Better for severe conditions
Compare with Definitions
10w30
Often recommended for older vehicles.
My mechanic suggested 10w30 oil for my high-mileage truck.
5w40
Thicker at high temperatures for enhanced protection.
In my high-performance engine, 5w40 offers superior protection under stress.
10w30
Balances cold weather performance and fuel efficiency.
I prefer 10w30 for its efficiency in mild winter conditions.
5w40
Suitable for newer vehicles and harsh conditions.
For my turbocharged car, 5w40 is the recommended oil.
10w30
A motor oil with moderate low-temperature viscosity.
I use 10w30 oil for my car in the spring and fall.
5w40
Provides better flow in extremely cold temperatures.
I use 5w40 oil for reliable engine starts in freezing weather.
10w30
Suitable for a wide range of temperatures.
10w30 is a versatile oil for varying weather conditions.
5w40
A motor oil with lower viscosity in cold conditions.
5w40 oil is ideal for my car during the winter months.
10w30
Provides good lubrication in moderate climates.
10w30 oil keeps my engine running smoothly in temperate weather.
5w40
Ideal for engines requiring higher viscosity oil.
5w40 keeps my engine protected even in demanding driving situations.
Common Curiosities
Is 5w40 good for winter?
Yes, its lower winter viscosity makes it suitable for cold climates.
Which oil is thicker at higher temperatures, 10w30 or 5w40?
5w40 maintains a thicker consistency at high temperatures.
What is 5w40 oil?
5w40 is a motor oil with a viscosity rating of 5 in cold temperatures and 40 at operating temperatures.
What is 10w30 oil?
It's a multi-grade motor oil with a viscosity rating of 10 in cold temperatures and 30 at operating temperatures.
Can I use 10w30 in any car?
It's best used as per the vehicle manufacturer's recommendation, typically in moderate climates.
Is 10w30 oil good for older engines?
Yes, its viscosity is beneficial for engines with higher mileage.
Which oil provides better fuel efficiency?
10w30 generally offers better fuel efficiency under normal conditions.
Can 5w40 oil be used in performance vehicles?
Yes, it's often recommended for high-performance engines.
Is 5w40 suitable for turbocharged engines?
Yes, its higher high-temperature viscosity is suitable for turbocharged engines.
Can I switch between 10w30 and 5w40?
It's advisable to stick to the manufacturer's recommendation or consult a mechanic.
Can using the wrong oil type damage my engine?
Using oil with inappropriate viscosity can lead to inadequate lubrication or increased wear.
Are these oils synthetic?
Both 10w30 and 5w40 can come in synthetic forms, depending on the brand and specification.
Does 10w30 oil work well in low temperatures?
It works in moderate low temperatures but not as well as 5w40 in extreme cold.
Should I use 5w40 in a heavy-duty engine?
Yes, it's suitable for engines that operate under severe conditions.
Where can I find the recommended oil type for my vehicle?
The vehicle's owner manual or a certified mechanic can provide this information.
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Written by
Tayyaba RehmanTayyaba Rehman is a distinguished writer, currently serving as a primary contributor to askdifference.com. As a researcher in semantics and etymology, Tayyaba's passion for the complexity of languages and their distinctions has found a perfect home on the platform. Tayyaba delves into the intricacies of language, distinguishing between commonly confused words and phrases, thereby providing clarity for readers worldwide.
