Can I Use 10W40 Instead Of 10W30? (Answer Explained)

A lot of questions arise when it comes to choosing the best engine oil. Well, this decision becomes hard to take as there are plenty of options available in the market. To choose the right engine oil, you must know your engine correctly. 

Today’s article will answer your questions, like- Can I Use 10W40 Instead Of 10W30? And many more. Here we have gathered all the features of 10W40, and 10W30 engine oil served on a silver platter. 

So, without any more delay, let’s get into details.

Can I put 10W40 instead of 10W30?

You should not put 10W40 instead of 10W30. It would be best if you stick to the exact engine oil mentioned in your owner manual. Different engine oils show various performances. Also, it works differently for every other engine. 

What will happen if you put 10W40 instead of 10W30?

If you use 10W40 instead of 10W30, you will see other performance improvements in your engine. Suppose your owner manual says to use 10W30. And you are using it for a long time. The engine worked great. 

Now, as you are using 10W30, we can consider you are driving in slightly cold weather. Because we already know, 10W30 is a cold, suitable low viscosity thin oil. So, even if you are replacing your engine oil, you must get one thin and low in viscosity. Now, let’s understand what will happen if you use the other one. 

First of all, your engine oil requirement wouldn’t match. Secondly, switching to 10W40, thicker oil can cause your engine damage. In cold weather, the oil often gets thick and lumped up. If you already use a thick oil, it will become thicker. 

As a result, the oil won’t be able to reach the engine components properly. They are resulting in less or zero lubrication. Without lubrication, friction and wear will take place and eventually damage your engine.

Note: If you want to use 10W40 to increase hot weather performance, you can go for a switch. But, still seek some professional help if you are new to wheelers, engines and oils.

Can you mix 10W40 and 10W30?

There is no yes or no answer to this question. Mixing between multi-grade oils doesn’t only depend on the grades. The engine’s running age, capacity and holding power also matter a lot. Besides, the oil brand you are choosing also is a fact. The same grade oil from the different brands could be individual.

To explain in general, it is not suggested to mix between 10W40 and 10W30. They are different viscosity oils and will react in another way when mixed. The chemical components will change, thus the performance. The change in viscosity can also affect your engine. 

So, it will be wise not to mix these two oils.

Comparison Chart – 10W40 vs. 10W30:

Higher viscosity oil
Lower viscosity oil
Thicker type of oilThinner type of oil
More suitable for hot temperatureMore ideal for cold temperature
Certified by Society of Automotive EngineersCertified by the Society of Automotive Engineers.
Available in synthetic, semi-synthetic and mineral categoryAvailable in synthetic, semi-synthetic and mineral category
Not recommended to use it interchangeablyNot recommended to use it interchangeably

In-depth Discussion – 10W40 vs. 10W30:

Even though the oil grades are the same from different companies, another brand of the same grade oil can be more or less effective because each company’s technology and processing are additional. 

From the below discussion, we will get to know about the specifications of each oil. 

What is 10W30?

10W30 is a multi-grade low viscosity thin engine oil. This kind of oil is more suitable for newer engines. This oil is specially designed for colder weather. If you are driving in a cold climate where your engine can jam due to cold, this oil is the solution for you.

This oil will not jam or get thick in cold weather. And will lubricate the engine appropriately to resist friction and wear. Also, you will get good mileage and running power using this oil.

What is 10W40?

10W40 is a multi-grade high viscosity thick engine oil. This kind of oil is more suitable for older engines. The oil is specially designed for hotter weather. If you are driving in an area where heat is a significant concern, this oil is the perfect choice for you.

In hot weather, engines face two kinds of heat. One is the outside heat, and the other is inside heat. So, it becomes a must to ensure such oil which can tolerate this strongness of heat. 10W40 will not get thin in the heat. It will be consistent with the viscosity and prevent metal to metal contact in the engine components. Instead of being a thicker oil, it doesn’t require extra pump pressure from the engine to work along.

What is the difference between 10W30 and 10W40:

When it comes to the comparison, you cannot call one oil thick or thin. It changes with the different multi-grade oils. Here we have 10W30 and 10W40. These two motor oils are really close to each other yet so further. Now we are going to figure out why it is so.

Viscosity Rating

10W30 and 10W40 have the same number 10 in the first portion. On the other hand, in the last part, one has 30, and the other has 40. The main difference between these two numbers is viscosity.

The first number of a multi-grade engine oil defines the cold temperature tolerance of the oil. The “W” with the first number means “Winter”. Thus, the first number is referred to as cold temperature tolerance. In this case, the lowest grade number with “W” means the oil is best suitable for cold weather.

Temperature Tolerance

The second number of the oil defines the hot temperature tolerance of the oil. A higher number of this grade means the oil is more suitable for the hot temperature. 

These two grades of engine oil also talk about viscosity. The viscosity doesn’t only depend on one number. A lower cold identification number oil means a lower viscosity thinner oil. On the other hand, a higher hot identification number of oil means a higher viscosity thicker oil.

In 10W30 and 10W40, the cold temperature tolerance number is identical. So, you can use both of the oil at cold temperatures. But, there will still be some performance changes. Why? Because the hot temperature tolerance number is not the same. As 40 is a higher number than 30, the 10W40 is higher in viscosity than 10W30. 


Does 10W40 hurt a 10W30 engine?

10W40 may hurt a 10W30 engine because they are different viscosity engine oils. Also, each of them is designed for various purposes.

What can I use instead of 10W30?

It is suggested not to switch your engine oil only if you don’t have any other option left without changing you can do it. 
If you are going to drive in hot weather, look for thick and high viscosity. Oil If you drive in a cold climate, you can put a thinner oil with lower viscosity in your engine.

Is 10W30 the same as 10W-40?

Yet 10W30 and 10W40 seem the same, but they are not. If you compare these two oils, 10W30 will come out as a thinner low viscosity oil than 10W40.

What is the best engine oil for hot weather?

Undoubtedly, a high viscosity thick oil is best for hot weather. Like- 5W40, 10W40, 20W50 etc.

Is 10W40 suitable for winter?

Is 10W40 suitable for winter?

Final Words

Now we have come across all the details of 10W40 and 10W30. From the above discussion, we can say that both oils are highly competitive with each other. The oils work in excellent insignificant conditions. 

The definition of the best engine oil could be different depending on each user’s need. But in general terms, 10W30 AND 10W40 both are excellent oils.

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