Can you mix engine oils – what happens when you mix engine oils?

Can you mix engine oils_

Mixing and matching bring with them a lot of excitement. It’s always fun to mix things, isn’t it? 

But, is it recommended?

It entirely depends on the situation. If you want to mix drinks to have a great time, that sounds great. But if you want to mix engine oils to boost the performance of your vehicle, you need to stop and think for a while.

Can you mix engine oils?

The first thing to shed light on is the very possibility of mixing engine oils. Is it even possible? The answer is yes. 

You can easily mix engine oils because they are mostly based on regular oil and are compatible with each other. Mixed oils will not have a major negative impact on the engine, at least in the short term. Back in the day, it was almost a sin to mix mineral and synthetic oil because it could damage the engine. But all that is far behind us now. Today, we can easily shift from one type of oil to the other based on weather conditions. People in colder regions do this all the time!

What happens when you mix engine oils?


From what we have researched and heard, vehicle owners mix engine oils to improve the efficiency of the engine and help it perform better. We are sorry to break the bubble but this is a myth. Mixing engine oils will have little to no effect on how your engine performs. If you mix various synthetic oil blends, in fact, the effects can be negative! In the long-term, the blends can react and cause problems to the engine.

Thus, even though at the surface, it feels okay to mix engine oils, you must be careful. Haphazardly putting two together will not give you any benefits.

Things to remember while mixing engine oils

Oils are miscible with each other, which means that they will not have any mixing issues. But there are things to remember. A few of them are as follows:


  •  It is always better to let the first grade of oil drain out before you change it. 
  • Don’t mix oils of two different brands because additives usually are different. They may not be compatible. In this case, the engine will suffer negative consequences.
  • It is okay to mix 5W30 and 5W40 oils.
  • Sticking to only one type of oil is the best bet unless you are in a sticky situation. For example, if you are stuck nowhere and need to top up the oil, you can use whatever is available instead of worrying about finding the exact same oil. 

Possible negative effects that you should be aware of 

  • The oil may lose its benefits. So, if you are using expensive oils, you won’t enjoy the premium benefits they promise.
  • The expensive additives (especially in the case of synthetic oils) will not work the way they are supposed to.
  • High-performance engines will not benefit from mixing. In fact, they may not meet the performance expectations, let alone exceed them.


Let’s gloss over a few questions that we think are on your mind.

1) Can you mix 5W30 and 10W30?

They are both 30 weight oils, which means you can mix them together. 

2) Can you mix different brands of synthetic oil?

In most cases, the answer is yes. Most synthetic oils are compatible not just with each other but also with conventional oils.

3) Can you mix different brands of 5W30 oils?

Yes. The only thing you should remember is the viscosity grade. If that’s the same, you don’t have to worry. For example, mixing 30 weight oils and 40 weight oils is not a great idea. But choosing different brands of 30 weight oils shouldn’t be a problem.

4) Will the wrong oil damage my engine?

Like we mentioned earlier, it’s all right as long as the viscosity grade is similar. If the additives are different and you did not wait for the current oil to flush out, you may face issues in the long run.

5) What happens if I put thicker oil in my car?

Your car will work harder to pump the oil. This means that the performance will go down and the fuel economy will become disappointing. Sludge deposit, chemical breakdown, etc. will also become common.

Bottom line – Can you mix engine oils?

Yes, but it is not going to give you any benefit. So, it is better to stick to the same (recommended) oil unless you have no choice. 

We hope this article helped you with the answers. If there’s anything we did not cover, please write to us and we will optimize our blog post accordingly.

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