Can You Mix 5W20 and 5W30? Is It Safe?

Written by

Charles Bolte


Vernon Hoppe 

Can You Mix 5W20 and 5W30

Most people ask, can you mix 5w20 and 5w30 oil? The answer is, if it’s only about mixing both oils, Yes, you can mix 5w20 and 5w30.

Is this mixing of oil recommended? The answer is No. Many factors are involved in this, like you won’t get the peak engine efficiency because of mixing, and there could also be a low lubrication effect.

Engines play a critical role there; most machines are more suitable with lighter oil 5w20 in colder environments than 5w30. It depends on the engine’s compatibility.

Read on to know the details.

About the 5w20 and 5w30 Oil Types

The 5w20 synthetic is a classified term for engine oil, which has multi-grade oil flow characteristics, even in a freezing temperature, i.e., it can be around -35*. Viscosity is shown by the number 5 at the lower temperature.

5w30 indicates the oil flow at a higher temperature, like 30*; however, the W stands for Winter. And number 5 stands for viscosity. It means the term 5w30 refers to the winter oil viscosity grades.

1. Potential Differences Between 5w20 and 5w30 Engine Oil

The difference between 5w20 and 5w30 is due to multiple factors. Let’s explore those potential factors which make 5w20 and 5w20 differ.


Characteristics 5w20 Engine Oil 5w30 Engine Oil
Temperature ● Suitable freezing Temperature in winter ● Suitable for higher temperatures in summer ( 95°F max)

● Can operate at low temperatures as well (about -22°F)

Fuel performance ● Better optimal performance due to less viscosity in a cold environment ● Slightly less optimal due to high density and better perform at high-temperature


Viscosity ● Lower viscosity

● Much thinner

● Slightly higher viscosity

● Much thicker

Oil change Duration ● 5000 miles to 16000 miles

● Depending on the type

● 3000 miles or after every three months for every conventional oil

● Ranges from 5000 miles or six months for synthetic oil

Types ● Conventional engine oil

● Synthetic 5w20

● Synthetic blend 5w20 engine oil

● Castrol Edge Synthetic oil

● Multi-grade oil

● Conventional 5w30 oil

Long-lasting Period ● Ranges to 10k miles between oil changes


● The period lasts around 20k miles between oil changes
Oil Consumption ● Slightly Low oil consumption due to low viscosity level – ENEOS 5w20 oil ● Higher level of oil consumption due to high viscosity
Price Range ● Between $25 to $40

● Varies according to type

● Varies according to type
Fluidity ● More fluid ● Less fluid

2. Possible Consequences for Mixing 5w20 and 5w30

If you have accidentally used 5w30 instead of 5w20 and need clarification on whether it is okay or not?

Both oils would mix, and this will not impact your car engine instantly. However, for this condition, it is recommended to do the oil change; it would help to prevent any damage.

However, below are what happens if you repeatedly mix 5w20 and 5w30 engine oil.

1. Poor Engine Performance


The engine performance can be damaged within a period if you mix 5w20 with 5w30 and don’t refill it with the required oil grade, as this mixing of oils isn’t suggested for the long term.

As both oils have different viscosity levels, any 5w20 and 5w30 combination could create engine problems.

2. Inefficient lubrication


Mixing the oils of different viscosities means both oils can’t give optimal performance. It would lead to poor lubrication for the engine parts and an inadequate burn rate.

However, due to insufficient lubrication, there are possible chances for sludge and dirt in the engine.

3. Engine wear and tear


Using the wrong oil rating will provide less lubrication to the engine’s moving parts, which will cause grinding.

As 5w30 is effective for protecting at higher temperatures and 5w20 is suitable at low temperatures, mixing this vicious oil will compromise its effectiveness.

Hence, the grinding will start causing wear in your car’s engine, which will cost much.

4. Leakage


Due to improper cooling of the engine, after the mixture of less vicious or highly viscous oil, the seals and gaskets of the motor could be damaged. This damage will be a potential factor for causing any leakage in your car system.

If you notice any leakage in the car, fix it immediately to avoid further damage.

5. Change in Colour


Any change in the viscosity of your car oil will start impacting the oil color; it will be more dirty and dark within the period.

6. Bad Odour


Sometimes, you may feel a bad fuming odor after mixing the 5w20 (thinner) and 5w30 (thicker) oil.

If you see any black smoke turning up, it means your car engine has not accepted this combination of oil and is reacting to it.

7. Costly Maintenance


As a result of any severe engine damage, it will need repairing. Hence you will be costed heavily if you do not adequately follow the manual instructions while mixing oil.

3. Under What Circumstances You Can Mix 5w20 and 5w30

There are a few circumstances when you can combine these two oils, but remember this mixing should be temporary. Let’s look out at those circumstances.

1. Emergency situation


If there is an emergency or you are in a dangerous area where you have no choice but to mix 5w20 and 5w30, it is better to mix it temporarily.

However, you must change the oil after getting back to normal situation.

2. Top-Off Situation


If you want to continue with your engine oil until the next maintenance check, mixing a smaller quantity of oil with the same viscosity would not harm the engine’s optimal performance.

Considerations: When is It Okay to Mix 5w20 and 5w30 Oil?

Mixing 5w20 and 5w30 is okay, although not recommended. Before mixing, consider these things properly for a better experience.

1. Check if both oils have the same brand and company.

2. Make sure that both oils have the same API classification.

3. Make sure both oils have the same classification manufacturers.

4. Consider following the vehicle manufacturer’s recommendation in the manual.

5. Make sure you’re mixing it temporarily; it is highly suggested not to use it as a permanent solution.


Can you mix 5w20 and 5w30? Enjoy your ride if you add 5w20 to 5w30 or mix 5w30 in a 5w20 engine. You can do the oil changing services after your journey because one or two-time oil mixing doesn’t immediately harm the engine.

It’s better to consult the owner’s vehicle manual to determine the recommended oil grade. Be mindful that this oil mixing is not advisable, so change it. Try to avoid this mixing as much as possible because every oil weight is made for specific engines and requirements. It’s better to maintain the normal alignment.

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