10w40 vs. 10w30 Engine Oil: Differences and Can You Swap Them?

The viscosity grade of every motor oil is an essential aspect of motor oil. It is a given that motor oil is a vital part of your engine. That is why you should understand the different types of viscosity. 

This promotes the ability to decrease wear and tear for your engine, improve your horsepower, and even improve your fuel economy. The 10w40 motor oil and 10w30 motor oil have been linked by most people. This is because both of these oils are multi-grade oil. 

They also perform well in standard and cold weather. You might not know any of the differences between 10w40 motor oil and 10w30 motor oil. In this article, we’ll focus on these two. Let us start.

10w40 vs. 10w30 Engine Oil

What Is the Difference Between 10w40 and 10w30 Oil?

10w40 motor oil and 10w30 motor oil have their similarities with each other. However, they also have their differences. So we will differentiate the differences between 10w40 motor oil and 10w30 motor oil in terms of fuel economy, hot weather, and viscosity.

Viscosity

Both 10w40 motor oil and 10w30 motor oil are known to be low viscosity oil grade. They also contain polymers that would speed up and slow down the thickening of the engine’s oil. Both 10w40 motor oil and 10w30 motor oil are available in the pure conventional form or high-quality synthetic grades. 

Both 10w40 motor oil and 10w30 motor oil can be used for summer use, but the 10w40 motor oil will protect your engine much better. This is because the temperature of your environment will not add to the heat of your engine, but it does affect the viscosity of your motor oil. This is the reason why the location is essential to determine the right motor oil for you. 

The 10w30 motor oil will run much smoother in cold weather. On the other hand, a 10w40 motor oil will also prevent wear and tear in hot temperatures.

Fuel Economy

A 10w30 motor oil is more common, and it is also the most available in the market. This is why it is not very expensive. A lot of car drivers prefer 10w30 motor oil to 10w40 motor oil. 

But you still need to find out if your manufacturer recommends this for your vehicle. The difference between 10w40 motor oil and 10w30 motor oil in terms of fuel efficiency is minimal. 

In theory, the 10w30 motor oil is considered to be more fuel-efficient than the 10w40 motor oil. So for the fuel economy, you need to use the motor oil that your manufacturer recommends.

Hot Weather

A 10w30 motor oil is a multi-grade oil. This means it has two viscosities. In addition, a 10w30 motor oil has the winter cold start flow properties. 

In the summer, it has a high-temperature thickness of thirty degrees. So the difference between 10w40 motor oil and 10w30 motor oil is their high-temperature viscosity. So the 10w40 motor oil is a lot thicker than the 10w30 motor oil in high temperatures.

Related: Can You Mix 10w30 and 10w40 Oil?

Can I Use 10w40 Instead of 10w30?

Yes, you can use it if you want to and if you have no other choice. However, this is not something that you should always do. You need to stick with the right motor oil for your vehicle. 

If you are living in hot weather, you should use 10w40 motor oil. This motor oil is designed to perform much better in hot temperatures, and it will also protect your engine from any wear and tear. Of course, you can still use 10w30 motor oil in warm weather, but it will thin out much quicker than the 10w40 motor oil. 

If you reside in a cold climate, you can use 10w30 motor oil to work much better for your vehicle. The 10w30 motor oil can also decrease the engine temperatures, and it will also heat up in the weather. The 10w30 motor oil is also more used than the 10w40 motor oil.

Accidentally Used 10w40 Instead of 10w30: Is It Ok?

Yes, it is okay. If you are worried that there might be some damages or failures in your engine, do not fret because it is okay. Both 10w40 motor oil and 10w30 motor oil can resist becoming solid in a zero degree Fahrenheit temperature. 

The 10w40 motor oil will retain its thickness or viscosity much longer than the 10w30 motor oil. This means that the 10w40 motor oil is thicker than the 10w30 motor oil.

10w40 vs 10w30 High Mileage

A 10w40 motor oil is recommended to be used for high mileage vehicles. The 10w40 motor oil is more vicious and thicker and thicker oils will help older engines to handle high temperatures and even manage to avoid wear and tear. If the motor oil will be thicker, it will reduce more tear and wear and provide an extension to the life of your engine. 

On the other hand, A 10s30 motor oil is good for high mileage vehicles. It has a formulation that has a mixture of high-performance synthetic base well-balanced additive components. 

Which Is Better, 10w40 or 10w30 Oil?

This depends on some things. One motor oil cannot be the best for every vehicle. You need to consider the ambient temperature and also the driving conditions. So before choosing between 10w40 motor oil and 10w30 motor oil, you need to refer to your owner’s manual for the recommended motor oil. 

There are slight differences between these motor oils. One of their differences is their temperature fluctuations, consumer preferences, and engine condition.

When Should I Use 10w40 and When 10w30?

You should use a 10w30 motor oil if you reside in an area where your climate is cold. This is because the temperature environment will not affect the heat coming from your engine’s operation. But still, you should be able to maintain the optimum maximum protective abilities of your motor oil.

 On the other hand, if you live in warm or hot areas, you want to go with 10w40 motor oil. This is a little bit important on hot days in the summer. In addition, both 10w30 motor oil will not protect your engine because they will thin out very quickly.

10w40 vs. 10w30

10w40 vs. 10w30 Toyota

The recommended motor oil for all Toyota engines is 5w30 motor oil. The 10w40 motor oil and 10w30 motor oil are not in the recommended list of motor oils for Toyota engines. You can use 10w30 motor oil for your automotive petrol or diesel engines and if you are in hot weathered places. 

You can also use 10w40 motor oil if the temperature is higher than ninety degrees Fahrenheit. It is still better, though, to refer to your owner’s manual.

10w40 vs. 10w30 Nissan

The recommended motor oil for Nissan vehicles is 5w30 and 10w30. The 10w40 motor oil is not in the recommended list of motor oils for Nissan engines. 

However, you can use 10w30 motor oil for your automotive petrol or diesel engines and if you are in hot weathered places. You can also use 10w40 motor oil if the temperature is higher than ninety degrees Fahrenheit.

10w40 vs 10w30 Subaru

The recommended motor oil for all Subaru engines is 0w20 and 5w30. The 10w40 motor oil and 10w30 motor oil are not in the recommended list of motor oils for Subaru engines. 

You can use 10w30 motor oil for your automotive petrol or diesel engines and if you are in hot weathered places. You can also use 10w40 motor oil if the temperature is higher than ninety degrees Fahrenheit. It is still better, though, to refer to your owner’s manual.

10w40 vs. 10w30 Mazda

Almost all the vehicles and SUVs of Mazda will need 0w20 motor oil. However, their lone standout might be used with some 5w30. The 10w40 motor oil and 10w30 motor oil are not in the recommended list of motor oils for Toyota engines. 

You can use 10w30 motor oil for your automotive petrol or diesel engines and if you are in hot weathered places. You can also use 10w40 motor oil if the temperature is higher than ninety degrees Fahrenheit.

10w40 vs 10w30 BMW

For all BMW engines, they are recommending 5w30 motor oil. The 10w40 motor oil and 10w30 motor oil are not in the recommended list of motor oils for BMW engines. You can use 10w30 motor oil for your automotive petrol or diesel engines and if you are in hot weathered places. 

You can also use 10w40 motor oil if the temperature is higher than ninety degrees Fahrenheit. It is still better, though, to refer to your owner’s manual.

10w40 vs 10w30 Ford

According to the 2020 ford owner’s manual, almost all of their engines must be using a 5w30 motor oil or 0w30 motor oil. The 10w40 motor oil and 10w30 motor oil are not in the recommended list of motor oils for Ford engines. 

You can use 10w30 motor oil for your automotive petrol or diesel engines and if you are in hot weathered places. You can also use 10w40 motor oil if the temperature is higher than ninety degrees Fahrenheit.

10w40 vs 10w30 Chevrolet

For Chevrolet, the recommended oil is 5w20, 5w30, or 10w30 in some engines. The 10w40 motor oil is not in the recommended list of motor oils for Chevrolet engines. You can use 10w30 motor oil for your automotive petrol or diesel engines and if you are in hot weathered places. 

You can also use 10w40 motor oil if the temperature is higher than ninety degrees Fahrenheit. It is still better, though, to refer to your owner’s manual.

10w40 vs. 10w30 Jeep

The recommended viscosity for jeep vehicles is 0W20, 5W20, 5W30, or 10W30. Unfortunately, the 10w40 motor oil is not on the recommended list of motor oils for Jeep engines. However, you can use 10w30 motor oil for your automotive petrol or diesel engines and if you are in hot weathered places. 

You can also use 10w40 motor oil if the temperature is higher than ninety degrees Fahrenheit. It is still better, though, to refer to your owner’s manual.

10w40 vs. 10w30 Volkswagen

Their recommendation is only 5w30 and 0w20. The 10w40 motor oil and 10w30 motor oil are not in the recommended list of motor oils for Volkswagen engines. 

You can use 10w30 motor oil for your automotive petrol or diesel engines and if you are in hot weathered places. You can also use 10w40 motor oil if the temperature is higher than ninety degrees Fahrenheit.

Summary

In summary, 10w40 motor oil and 10w30 motor oil are sometimes getting swapped by some car drivers. Both of these motor oils have their differences, but they also have their similarities. 

Still, you should refer to your owner’s manual to find the right and suitable motor oil for your engine. Your owner’s manual is the one that knows what is best for your engine.

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My name is Hank, and I've been in the automotive industry for 27 years. I've been working in my own auto repair shop for the last 13 years, and now I want to help you here, on my blog. Let me know if you have any questions. Read more