Can You Mix 5w20 And 10w30?

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Mixing two oils of the same viscosity but different weight is safe, mixing two oils of different viscosity but the same weight is also safe. So, can we say that mixing oils of different viscosity and different weights is safe? Can you mix 5w20 and 10w30 engine oils?

When it comes to mixing motors oils, we don’t recommend such an act. But, you could get stuck in the middle of a trip due to a lack of oil in the engine.

Sometimes, when such scenarios occur, you may be unable to get the selfsame oil your engine is currently using; thus, you’re left with no choice but to top up another oil.

Can You Mix 5w20 And 10w30?

Generally, when you mix two oils of different weight or viscosity, the mix won’t actually cause any damage to your engine because both oils will keep lubricating the engine components. However, mixing oils will not improve your car engine’s performance at all.

This is because the additives in the oils are there for different reasons. The incompatibility of these additives would cause your engine not to get the full benefits it should have gotten from the oils if they were not mixed.

Regarding 5W20 and 10W30, the effect of mixing these oil depends on your car. Which of them was your car designed to run with? 5W20 or 10W30? Your car manufacturer’s recommendation notwithstanding, mixing 5W20 and 10W30 won’t cause any harm to your engine.

However, some drivers allege that it is safer to mix two straight weight oils or multigrade, instead of mixing straight weights with multigrade.

5W20 will flow easier in cold/low temperatures to keep your engine parts lubricated at all times. On the other hand, 10W30 will flow in cold/low temperatures, but the flow speed will be slower than that of 5W20.

What Happens When You Mix 5W20 and 10W30?

What Happens When You Mix 5W20 and 10W30

There are many different types of motor oil (classified by weight and viscosity), but 5W20 and 10W30 happen to be the most popular options used by many drivers. When you top up 5W20 to an engine that has been running 10W30, you won’t notice any significant problems.

Basically, 5W20 would run your engine smoothly during the winter seasons, thanks to its low viscosity rating. On an important note, oils do not actually blend or mix as we frequently say.

What happens is this, when you pour in 10W30 into an engine that has 5W20, the 10W30 would stay separate and won’t blend.

So, basically, you are going to have a few quarts 5w20 and a quart 10w30. Both oils won’t mix to form a single oil. But in all these, there’s nothing wrong with using two different oil weights for one engine. You just need to know that you may have less time between oil changes as a result of mixing oils.

However, if your engine is meant to use lighter oils, introducing thicker oils to the engine may lead to an increase in fuel consumption.

Why? The increase is because your car engine is likely to utilize more energy to pump the thicker motor oil; thus, consuming more petrol.


Can you mix 5W20 and 10W30? Yes, you can mix both oils. But just as you may already know, mixing of motor oils is not advisable because it guarantees no particular advantage. Also, this act can void the warranty coverage provided by your car manufacturer.

We’d rather advise that you stack up more of the recommended oil for your car and save on your car. So, when an emergency strikes, you can easily get out the oil, top-up, and continue driving. It is more advantageous to use one particular type and weight of oil for your car.

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