Can You Mix Fully and Semi Synthetic Engine Oil? (Explained)

You might have heard about synthetic oils if you are familiar with engines and vehicles. Synthetic oils can be of different types, and for example, fully synthetic, semi-synthetic, synthetic blend, etc., are different types of synthetic engine oils.

Generally, mixing different types of oils are not recommended. But you might be confused about whether you can mix thoroughly and semi-synthetic engine oil or not. You have to know the safety of mixing fully synthetic and semi-synthetic engine oil. Moreover, knowing the consequences, advantages, and disadvantages of mixing these two oils is also essential.

Can You Mix Fully And Semi-synthetic Engine Oil?

You can mix fully synthetic and semi-synthetic engine oil. Full synthetic and semi-synthetic oils are compatible with each other. Generally, mixing fully and semi-synthetic engine oil doesn’t create a big problem. But like other oils, mixing two different oils is not recommended.

However, synthetic oils can be of different types. But each synthetic oil has different additives and ingredients. For example, fully synthetic engine oil doesn’t have other conventional oil mixtures.

But semi-synthetic oil is not pure synthetic oil. Generally, mineral oils are present in semi-synthetic oil. But you can mix full synthetic oil with semi-synthetic oil. Because both of them are synthetic oils.

If you mix these two oils, the full synthetic oil might be diluted. So, you might not get the best performance of the engine like the full synthetic oil. Moreover, the additives of the semi-synthetic oil will get mixed with the full synthetic oil. This might lead to destabilizing of the full synthetic oil.

As we always recommend not to mix two different types of oils. One type of oil can contaminate another one. But mixing full synthetic and semi-synthetic oil will cause no harm to the engine dangerously. If you mix these two oils and continuously use the mixture, the performance might get interrupted gradually.

Many people use semi-synthetic oil with full synthetic engine oil to reduce the cost. Full synthetic oil is pretty costly since it is the pure one. Also, full synthetic oil is made of synthetic base stock. So, mixing semi-synthetic oil with it will reduce the cost of engine oil.

You can add 25% to 50% of full synthetic oil with semi-synthetic oil. The fully synthetic oil you will add, the better performance of the engine you will get. So, if you want to use engine oil by mixing two of the synthetic oils, you can do it. But mixing two oils is not recommended as always.

Three reasons why you can mix semi-synthetic and fully synthetic oil

Now that you know you can mix semi-synthetic and fully synthetic oil, you might want to know the reasons. Because if you are concerned with the safety of mixing oils, you have to ensure that. So, let’s see the reasons why we can mix semi-synthetic and fully synthetic oil.

Safe mixture:

Generally, when we mix two different types of oils, we think about safety first. But mixing full synthetic and semi-synthetic oil doesn’t create unsafe situations in the engine.

Sometimes, the performance of the engine might not be best after mixing semi-synthetic oil. But semi-synthetic oil can be a good substitute for full synthetic oil.

Compatible oils:

You can’t mix two different types of oils effectively if they are not compatible. Generally, different forms of synthetic oils are compatible. So, if you mix full synthetic oil with semi-synthetic engine oil, they will also be compatible.

The oils will not be contaminated with less efficient materials. Full synthetic oil might get diluted. But this doesn’t mean that semi-synthetic oil will not work. Semi-synthetic oil is another type of synthetic oil mixed with mineral oils. So, they are easily compatible.

Cost-effective:

Another good reason for mixing semi-synthetic and full synthetic engine oil is the cost-effectiveness. Generally, the cost of fully synthetic engine oil is higher than other forms of synthetic oil.

But if mineral oil or conventional oil is mixed with it, the oil becomes less costly. So, people also mix these two oils to reduce the cost.

What happens if you mix semi-synthetic and fully synthetic oil?

There must be some consequences when you mix semi-synthetic and fully synthetic oil. It might not create a big problem, but some issue might arise after mixing the two oils. So, let’s see what happens if you mix these two synthetic oils.

Dilution of oil:

Generally, when you mix semi-synthetic oil with full synthetic oil, the oil will be diluted. Full synthetic oil is entirely pure. So, if you mix mineral oil or semi-synthetic oil, the pure oil will be diluted. For the dilution of oil, the purity of the oil is also get reduced.

Reduced performance:

The performance of the mixed oil will be reduced. This doesn’t mean that the performance of the oil will be wrong. But it will be obviously less than the full synthetic oil. Generally, the full synthetic oil lubricates well and provides better corrosion protection to the engine. So, when you mix semi-synthetic oil with it, the lubrication ability and corrosion resistance reduce.

Oil destabilization:

Sometimes, the additives of the full synthetic oil and the mineral oil of the semi-synthetic oil react. For this reaction, the oil might get destabilized. So, destabilization of oil can minimize the performance of the engine oil.

Fully Synthetic Oil Vs Semi-Synthetic – What are the differences?

You might have already known that fully synthetic oil and semi-synthetic oil are not the same. These two oils have some fundamental differences. So, let’s see the differences between fully synthetic and semi-synthetic oil.

Purity:

Generally, fully synthetic oil is pure synthetic oil. This oil might have some additives to boost its performance. But fully synthetic engine oil doesn’t have other conventional oil or mineral oil. So, full synthetic oil is 100% pure.

On the other hand, semi-synthetic oil is not pure synthetic oil. It has a mineral oil mixture with synthetic oil. Generally, in semi-synthetic oil, 25 to 50 % of synthetic oil is mixed with mineral oil.

Ingredients:

The ingredients in full synthetic and semi-synthetic oil are different. Generally, full synthetic oil has some additives. These additives make the synthetic well perform better. But the semi-synthetic oil has full synthetic oil and mineral oil in it. So, the ingredients in these two oils are different.

Performance:

The performances of a full synthetic oil and a semi-synthetic oil are different. Generally, full synthetic oil performs better than semi-synthetic oil. The more pure the synthetic oil is, the better performance it will provide. Semi-synthetic oil is not efficient as the full synthetic oil since it has a mineral oil mixture in it.

Cost:

The costs of fully synthetic oil and semi-synthetic oil are different. Full synthetic oil is more expensive since the oil is purer. But the semi-synthetic oil is pretty cost-effective.

What to do if you mix semi-synthetic and fully synthetic oil?

Generally, mixing semi-synthetic and fully synthetic oil is not so dangerous that you have to take immediate action. Mixing semi-synthetic oil with fully synthetic oil is generally making the fully synthetic oil diluted.

So, there is no danger to mix these two synthetic oils. But if you want to get the best performance or switch oil, you can do it. If you want to use fully synthetic oil or semi-synthetic oil separately, you have to flush out all the oils from the engine.

Then you can use the oils separately or use any of them. But if some of the oil gets mixed with another synthetic oil, it will not create any significant problem.

Is fully synthetic oil better than semi?

Yes, fully synthetic oil is better than semi-synthetic oil. Because fully synthetic oil has some better properties. For example, the performance of fully synthetic oil is better than semi-synthetic oil.

Moreover, fully synthetic oil lubricates better than semi-synthetic oil. Also, full synthetic oil provides more protection than other synthetic oils. The purity is more in fully synthetic oil. So, the full synthetic oil provides better performance overall.

But the cost of fully synthetic oil is more than the semi-synthetic oil. Now, this depends on you that whether you want better performance or cost-effectiveness. But in general, full synthetic oil is better than semi-synthetic oil.

Final Thoughts

Fully synthetic oil and semi-synthetic oil can be mixed. But mixing different oils are not recommended. Because the properties and performances get reduced after mixing oils. But you can mix these two oils because they are compatible. Moreover, the cost will also be reduced.