5w30 Vs. 5w40: Which Oil Is Suitable For You?

Considering between 5w30 and 5w40?

If this is your concern, then you are on the right path.

Today I’m going to show you the similarities and differences between these oils and why you should use one instead of the other. 

In this comprehensive article, I’ll cover:

Let’s get started!

5w30 Vs. 5w40: Similarities And Differences

To help you make up your mind, let’s take a quick look at the image below.

5w30 vs. 5w40 comparison

Warm Temperature Viscosity 

The number “30” in 5w30 indicates the viscosity of the oil at a higher temperature (212℉). The same applies to 5w40 oil. 

This means 5w30 motor oil has a lower viscosity than 5w40 one. In other words, 5w30 is thinner than 5w40. 

That’s why 5w30 is superior to the 5w40 motor oil regarding overall car performance.

Oil Flow

Due to its lower viscosity, 5w30 has a faster oil flow compared to 5w40. With this benefit, you will find it much easier to start your engine with 5w30, especially in the wintertime. 

Fuel Economy 

As 5w30 is thinner and can flow faster. The engine does not have to work hard to move all the car parts while driving. 

This results in less fuel consumption. 

The opposite is true for the thicker 5w40.

5w30 vs. 5w40: Applications

The region temperature is always higher than 95℉

When the weather gets higher than 95℉, 5w40 is the better choice. 

This is because the temperature range of 5w40 is much wider, around from -22℉ to 122℉, while 5w30 can only function well between -22℉ and 95℉. 

The region temperature fluctuates from -22℉ to 95℉

In fluctuating temperature conditions,  if you are living in a place where the temperature range is approximately from  -22℉ to 95℉, both 5w30 and 5w40 may work on your engine. 

However, during wintertime, you should go for 5w30 since it’s thinner. It saves you a lot of time starting your engine. 

NOTE: You should note that you can use both 5w30 and 5w40 in most conditions. However, one is much better than the other for specific situations. 

5w30 vs. 5w40 application

Case #1: With higher-performance engines and loads than the norm, I recommend using 5w40 oil in your vehicle, thanks to its thickness.

Case #2: You are a citizen who normally gets stuck in traffic jams or drives at high speed. 5w40 will help you get through all of these troubles more easily.

Case #3: You are more familiar with long trips requiring greater fuel consumption, like driving to work every single day without any heavy stuff in your car. 5w30 oil is for you.

Case #4: The higher your vehicle’s mileage, the thicker the oil needed. If you have a high-mileage car by now, go for 5w40. 

DON’T FORGET to change oil type depending on your vehicle mileage for better performance.


I believe you now know all the common features and differences between the two oils: 5w30 and 5w40. Your last job is to choose wisely the oil that is the most suitable for you. 

Here are my top choices for the best oil of each type:

Mobil 1 Advanced Full Synthetic Motor Oil 5W-30

Mobil 1 Advanced Full Synthetic Motor Oil 5W-30


Castrol EDGE 5W-40 

Castrol EDGE 5W-40


And now I’d like to hear from you.

Is there any case you encountered that has not been mentioned above?

Let me know by leaving a comment below right now.


1. Can I Use 5w40 Instead Of 5w30?

Yes, but only on older cars and trucks.

Because old vehicles don’t have variable valve timing and lift controlled by engine oil pressure technologies, the two oils are basically interchangeable. 

However, most latest model cars and trucks use these technologies. Different thicknesses can affect oil pressure. Thus, it can impact how these systems function. 

This is why you have to stick to the manufacturer’s recommendations for the best performance.  

2. Can You Mix 5w30 And 5w40 Oil?

Yes, but not recommended.

It is a best practice not to mix engine oils of different viscosities since it can cause engine damage in the long run.

I suggest you follow your owner’s or service manual’s recommendations.

But overall, if your vehicle calls for 5w30, but it is unavailable, or you don’t want to spend the extra money, 5w40 will be a suitable alternative.

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