15w40 vs 15w50 Engine Oil – Which is Better?

It’s best to keep in mind that engine oil is used for all automobiles, such as motorcycles, generators, cars, and all different kinds of machinery.

Using these oils will definitely prevent wear and tear in all the parts of the engine, not only that, but it will also lubricate the moving parts within your engine. It’s safe to say that having high-quality motor oil is an identifier of how long your engine will last over a period of time.

Engine oil helps to keep your engine cool and it will prevent overheating from happening. Its job is to divert the heat that is been produced by the moving parts. This is why it is important to get an oil change on a regular basis.

As a vehicle owner, it is your point of duty to know the importance of engine oil when it comes to your car’s engine. Apart from that, you should also know the different types of motor oils and how they differ from each other.

In this article, we will be taking a look at the 15w40 vs 15w50 engine oil. We also compared them so that you can have a better understanding.

15w40 vs 15w50 Engine Oil

15w40 vs 15w50 Engine Oil

As we have mentioned above, engine oil helps to lubricate the internal components of the engine. While your car is running, the moving parts will begin to wear, so it is very essential to lubricate your engine by using engine oils.


When it comes to viscosity, the 15w50 engine oil is said to have a higher viscosity when compared to 15w40 oil. With the 15w50 full synthetic oil, you will get next-level protection and lubrication. Apart from that this amazing oil is widely known for its long drain intervals, so after traveling for a while, you can take the time out and change the oil.

However, the 15w40 engine oil is the best option for diesel engines and it performs well in hot weather conditions. Even though the 15w50 is said to have a higher viscosity than the 15w40, low and high-temperature oil viscosity is pretty much the same for both oils.

Fuel Economy

We think that the 15w40 engine oil is the perfect fit for new vehicles, especially in cold weather. However, to get the best gas mileage, it is always best to use the oil that is recommended by your car’s manufacturer. Engines that crave the best performance should go with the 15w50. Even if it’s a case where your machine is overworking in hot temperatures, you should still go with the 15w50 motor oil.

Another thing that you can do is use the 15w50 in your turbocharged engine. However, there is no doubt that the fuel economy is similar between both of them. To benefit from fuel efficiency, you should use the correct oil for your vehicle.

Weather Condition

You can without a doubt use the 15w40 engine oil in both hot and cold weather conditions without experiencing any issues. If you’ve read the label and see that the oil number is 15, it doesn’t simplify that the temperature will always be limited to 25°F.

There is definitively a relation between the low first and low second numbers. We think it would be better if you use thin oil during the winter seasons. So, the 15w40 engine oil is the right choice for winter. On the other hand, the 15w50 engine oil is great for hot and cold conditions.

15w40 vs 15w50 Oil – Which is Better?

Let’s start by saying that the 15w40 is a great engine oil that is recommended for a heavy-duty engine in hot and humid conditions. However, we don’t think it would be a good idea to use the 15w50 since your machine may not be able to work with it.

In terms of cold weather, this oil helps to reduce horsepower. Another thing to keep into consideration is engine temperature. As we’ve stated before, it is best to use any oil that is recommended by your car’s manufacturer.

15w40 vs 15w50 For Toyota

When it comes to Toyota, the recommended engine oil to use is 5w30. It’s best to keep in mind that the 15w50 and the 15w40 motor oil are not included in the same list which means that they should not be used.

The 15w50 can be used in high-performance engines, while the 15w40 oil can be used in gasoline engines.

15w40 vs 15w50 For Ford

There is no doubt that almost all Ford engines stick to using the 15w30 or the 0w30 motor oil. However, you can still use the 15w40 and 15w50 motor oil if you want to, but they are not included in the recommendation. It’s always to read the owner’s manual and read the recommendation.

15w40 vs 15w50 For Jeep

When it comes to Jeep, you can go ahead and use 0w20 or 5w30 motor oil, depending on the model you own. However, you may not see the 15w40 or 15w50 in the recommendation list, but you can use them if you think it’s best for your vehicle.

15w40 vs 15w50 For Nissan

Let’s start by saying that the recommended oil that should be used in a Nissan vehicle should be 5w30 and 10w30. The 15w50 and 15w40 motor oil is not suitable but you can still use them if that’s what you want and you think they can be beneficial for your Nissan engine performance.

15w40 vs 15w50 For BMW

All BMW engines are recommended to use the 15w30 motor oil. Even though the 15w50 and 15w40 are not on the recommended list, you can still use them if you want, but they might not be the best option. The 15w50 works well for high performance, while the 15w40 is designed to be used in gasoline engines.

FAQs – Frequently Asked Questions

Q. Can you mix the 15w40 with the 15w50 motor oil?

No, we don’t think this is a good idea. The reason for this is that the 15w50 is known to contain slightly more viscosity compared to the 15w40. What this means is that the 15w50 is considered to be the heavier oil. Heavy oil doesn’t have good temperature protection. So, if it’s a case where you mix them, it can cause damage to your engine.

Q. Can I use 15w40 motor oil on my bike?

We think you can, but we don’t think it is safe to do. It has a lot to do with the bike manufacturer’s specifications. As you may already know, most bikes tend to have a clutch, and using the wrong oil can cause the clutch to slip. However, If you have a Honda Super Cub, then the 15w40 engine should be just fine.


All engines require the right motor oil to get them going. This is why it is very important to know the right oil for your engine as this will improve its overall performance and extend its lifespan.

However, the 15w50 motor oil and 15w40 are suitable for their recommended engine. As you can see, both oils come with their unique features as well as advantages. But, before using them make sure to read your owners manual just to be on the safe side.