Can You Mix Different Weights of Oil?

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Can you mix different weights of oil? That implies to ask if it is possible to mix two oils of different viscosity. Well, let’s get practical here – have you ever mixed two different spirits? How was the taste and feel when you drank the cocktail?

Apparently, it’s hard-hitting. Now, can we arrive at the conclusion that mixing different weights of oil can lead to something serious?

The answer is no, but here’s what you should know about blending oils of different viscosity.

Why Is Oil Very Important In Cars?

Every automobile runs with metallic rotors that need constant lubrication to function effectively. Oils are the only way to keep these metals lubricated, free from rust, and working as expected.

The engine (powerhouse) in an automobile or machine will definitely breakdown if not fed with a considerable amount of oil quite frequently.

However, the continual efficiency of your engine depends on the type of oil you use in the car. Not all oils are actually good for your engine; hence, your car manufacturer would always recommend the type of oil you should use o the car.

Still again, for one reason or another, it may be difficult to stick with the recommended oil. More so, emergencies may leave you with no choice but to mix different oils or use a contradicting oil just to serve the moment. But, you should know about the different types of car engine oils your car needs to function.

Types of Car Engine Oils

There are quite different types of engine oils – the list includes mineral/regular oil, semi-synthetic oil, and pure synthetic oil. Each of these oil types has unique advantages and work best on specific engines – they also have disadvantages and vary in pricing.

Oils are typically weighed based on viscosity, and since different oils contain different additives, so their viscosities differ. Generally, it is safe to use a blend of different oils for your car engine, but there are things to consider, else, you may be paving the way for a major engine breakdown.

Can You Mix Different Weights of Oil?

Can You Mix Different Weights of Oil

Basically, semi-synthetic oils and pure synthetic oils are compatible, but the additives differ based on the manufacturer.

Thus, when you mix these two types of oils, it does not “known” harm to your car engine or other metallic components. Your engine would definitely run smoothly with this blend; however, the time between “oil change” may be shorter due to the blend.

Discussing “Mineral Oils,” they are also good for car engines regardless of the type of vehicle. Besides, mineral oils are all byproduct of the same petroleum feedstock.

When you mix different weights of oil, due to the varied amount of additives in the two oils, it may not provide the same efficiency compared to when you use one of the oils constantly.

Different oil viscosities do not separate or react negatively, and this is because the base oil is almost the same in terms of molecules. Various car engine oil manufacturers have assured their customers that it is definitely safe to mix different weights of oil.

For example, 5W30 has low viscosity and 10W40 has higher viscosity; when these two oils are mixed, the resulting blend will simply have viscosity characteristics thicker than 5W30 but thinner than 10W40, and this poses no harm to your engine.

This also doesn’t mean that the oils are incompatible; the only thing that happened is the re-balancing of the viscosity characteristics.

But what’s your reason for mixing oils? Could it be an emergency or you’re running a shortage of your normal oil? There’s no proven benefit from mixing different types or different weights of oil. Your engine typically performs

What Happens When You Mix Different Types of Oils

There’s no known danger in mixing synthetic and conventional motor oil. Nevertheless, the presence of conventional oil will reduce the performance of the synthetic oil; thus, your engine won’t enjoy the full benefits of using synthetic oil.

Also, you can use a blend of engine oils from the same brand; it’s totally safe. Nowadays, synthetic oils are fully compatible with conventional oils, so you can mix the two.


When people ask, “can you mix different weights of oil?” our strong recommendation remains to stick with your car manufacturer’s specified oil since there’s no added benefit in mixing oils.

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