Can I Mix 10w30 With 5w30 [You Must Know]

You just put oil back in your car after drilling and tapping the oil pan. You got 3 quarts put in when you realized that one of them was 5w30 and the others were 10w30. And this unwilling oil-mix mistake brings this question to your mind: Can I mix 10W30 with 5W30? Will it damage my car engine, or do I need to drain the oil?

Fortunately, we are here to answer your questions and let you know the effects of mixing 10W30 and 5W30. So, read on till the end. 

Can I Mix 10w30 With 5w30

Yes, you can mix 10W30 with 5W30. They will blend perfectly. Both these two engine oils will act similarly. Plus, both of them have the same viscosity at temperatures. As the viscosity of these two oils is very close, they will mix properly. So, we can say you can mix 10W30 with 5W30 safely and perfectly. 

We recommend you take a look at your car manufacturer before mixing oils. If the manual recommends 10W30, you can pour 5W30 or the mix without any hesitation. On the other hand, it is better to stay with 5W30 if the manufacturer recommends 5W30 as the mixture will not pump well at very cold temperatures. 

However, we suggest staying with the particular engine oil recommended by the car manufacturer. In doing so, you will get the most benefits out of the oil than switching to DIY blends or other oil types. 

Therefore, oils with the same weight but different viscosity may be the same at operating temperatures. But they won’t remain the same when cold. The thinner or less viscous oil will easily flow to the top ends. 

In short, mixing 10W30 with 5W30 is okay and it doesn’t pose any harm to your engine. But it’s better to stick with the oil your car manufacturer recommends. 

Note: You can also read Can You Mix 10w30 And 10w40.

What Happens If You Mix 10W30 With 5W30?

It won’t hurt anything or damage your engine if you mix 10W30 with 5W30. You will just miss some cold flow benefits of 5W30. Technically, the mixture will still be 10W30 as there is no difference between rating numbers. 

The number (30) next to W is the actual weight of the oil when your engine is at operating temperatures. And the number before W is the cold rating. At low temperatures, the viscosity of the mixture will be different and the moving parts of your engine will not get the most benefits of the oil. 

The 5W30 engine oil is thinner than the 10W30. So, it can easily flow to the top ends when cold. On the other hand, 10W30 is thicker and perfect for vehicles that carry heavy loads. 

However, the oil blend of 10W30 and 5W30 doesn’t cause any damage to your engine. It only voids the warranty coverage. 

Is It Ok To Mix 5w30 And 10w30?

Yes, it’s okay to mix 5W30 and 10W30. You can mix these two oils and pour the mixture into a vehicle running on 5W30. 

However, you may not get your expected output by mixing these two oils. Each engine is specially designed with a specific weight of oil in mind. Combining two different weights or grades results in an oil that doesn’t work the way that the engine manufacturer intended.

Besides, both (5w30 And 10w30) have different grades. The 5w30 is lighter and less viscous, which makes it ideal for light usage. On the other hand, 10w30 is thicker and perfect for vehicles that carry heavy loads. 

Indeed, it’s not bad if you mix 5w30 And 10w30 and you can safely pour it in the engine. However, it’s better to play the game safely and pick the right engine oil.


Is it OK to mix different weights of motor oil?

No, you can’t mix different weights of motor oil. However, you can blend or combine different viscosity grades of oil from the same brand. 

Is it OK to mix 10w40 with 10w30?

Yes, you can mix 10w40 with 10w30 if you don’t live in freezing weather. But, it’s advisable to not combine these two oils as they will boost up oil pressure when cornering at high revs.

Can I use 10w30 instead of 5W-30?

Yes, you can use 10W30 instead of 5W30 as they have very close viscosity. So, it doesn’t bring any harm to your engine if you put 10W30 instead of 5W30. 

Is 10w30 thicker than 5w30?

Yes, 10W30 is thicker or more viscous than 5W30. In other words, it has higher viscosity when it is cool. 

What is the difference between 5w30 and 10w30?

The main difference between 5W30 and 10W30 is their thickness. The 5W30 is thinner and more efficient than the 10W30, and it can easily reach the difficult parts of the engine at low temperatures. On the other hand, 10W30 is thicker and perfect for higher-capacity engines. 


Throughout this guideline, we break down the answer to the question: Can I Mix 10W30 with 5W30? Yes, you can mix them as the viscosity of these two oils is very close and they blend perfectly. And it doesn’t cause any damage to your engine if you pour the mixture of these oils. 

However, we recommend you to not mix these oils unless you are in an emergency situation. 

About John M

John contributed as a technical head at an automobile company just 2 years after his post-graduation in Automobile Engineering. He loves to lead a free life, so he left his job & started blogging. Now, he does research on every automotive problem, part & product and seeks a better solution & best products & shares his findings with his readers to help them as well as to minimize their struggle.

Leave a Comment