Can You Mix Different Weights of Oil? (Explained)

One of the most important things a car or any vehicle needs to work properly is the oil, right? The time has come, and you want to change the oil in your car, but when you check out the stock, there are different weights of oil hanging around.

The first question that comes to mind is “can you mix different weights of oil?”

There are a lot of sayings about this “issue” and I am here to clear it all for you! Let’s find out whether you can do a mixture of oils in your cars!

So, Can You Mix Different Weights of Oil?

The important thing to know in this case is that the mixture of different weights of oil isn’t something recommended or preferable.

The main answer about mixtures of the weight of oils is no! You shouldn’t combine everything you see laying around in your garage.

Even though most people mention that they have mixed weights of oils in their cars and it isn’t something that cannot be done, avoid it as much as you can.

First and foremost, the weight of oil mainly refers to the viscosity that the oil has. So, can you mix different weights of oil? Well, that’s not really the question you should be asking and let me show you why in the following section down below.

Why You Can’t Mix Them? – Factors to Have in Mind

After saying that mixing different weights of oil in a car isn’t the proper thing to do, you should know which are the factors that lead to this answer, and basically, you should know what could happen to your vehicle if you try to mix things up.


The brand is one of the most important things to have in mind when it comes to oil in general, and that’s because not all of them are the same, and not all of them bring the exact same oils when it comes to specific weight or viscosity.

If you mix two different oils from two brands, you will encounter complete damage to your car’s motor, which will lead to complete failure.


Additives are the chemical compounds that make oil, basically, they are everything that is found in a bottle of oil. So, mixing two types of oil leads to mixing different types of additives as well.

The additives an oil has are the main factors that deal with the modification of weight/viscosity. A reason to check them as much as you can, and not mix them in any way, as you can experience a complete shutdown of the car in minutes.


In terms of type, there are four types of engine oil you may encounter and they include conventional oil, synthetic oil, synthetic blend oil, and high-mileage oil.

  • Conventional Oil – this is the most common type of oil that works perfectly on late-model cars.
  • Synthetic Oil – is the perfect type to use in your car as it brings out the best in whole-engine performance.
  • Synthetic Blend Oil – is the perfect combination of the most commonly used oil which is the conventional and synthetic oil.
  • High-Mileage Oil – is perfect for older engines, the ones that have already achieved 75,000 miles already.

Everything being said, every type of oil is different from one another and has different purposes, so putting them together in a car would be a definite disaster and you would be left without anything.

Understanding the Weights of Oil

So, as I mentioned at the beginning, the weight of oil doesn’t mean the fluid oz it comes at or just the weight of a bottle, instead, weight in oil refers to the viscosity it has and the way how it flows in different temperatures.

In bottles of engine oils, you surely have noticed some numbers and letters, and all of them have a role to play and they all show something you should definitely have in mind.

SAE in Oil

SAE refers to the Society of Automobile Engineers, which makes it obvious that the letters or the numbers following it are adjusted by this society and everything is sure.

W in Oil

The letter W is the one that leads to the flow of the oil during cold temperatures, and W in this case stands basically for winter!


The letter W is always followed by a number and it can be 30, 40, 50, and so on. This number that is added is the reason you are here, and it shows the weight of the oil. Basically, the higher the number, the thicker the oil is and the lower the number, the thinner the oil.

The most common weight of oil used in cars is 0W-40.

Choosing the Right Oil for Your Car

Nowadays, there are tons of engine oils on the market, and it seems like they are out there to confuse us, even more, when choosing the right oil for our cars.

However, you can choose the right oil just by checking out the manual of your car that comes from the car manufacturer! Every car has its own oil recommendation, so don’t panic.

Choosing the right oil for your car isn’t as complicated as it sounds!

Also Read: Ford Expedition Years to Avoid: Things To Know

Final Words

As we are here at the end, I want to mention again the fact that you shouldn’t mix any kind of oil weight and put them in your car as it can lead to different damages to the whole engine, especially on the motor!

Anyways, I hope that in the article you have found everything you needed to know about the weights of oil in general! Good luck and remember to not mix them!