Is It Okay to Mix Different Engine Oils?

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Normally, engine oil changes do not involve mixing oils of different grades.

However, if it becomes necessary to top up the engine oil because the level has dropped, the question arises: can oils of different grades be mixed? This article by Motorist has the answer for you.

How do engine oil grades differ?

Engine oil grades indicate their viscosity, which measures the oil's resistance to flow. Common examples include 0W-20, 5W-30, and 5W-40, with the following meanings:

• The number before the 'W': Indicates the oil's ability to remain fluid at low temperatures (winter conditions). The lower the number, the better it flows in cold weather.
• The number after the 'W': Represents the oil's viscosity at high temperatures (when the engine is running). A higher number indicates thicker oil.

Engine oil suitability for different car models

The appropriate oil grade varies depending on the car model and engine type. Even vehicles of the same model might require different oil grades if they use different engines. Therefore, you should always follow the viscosity recommendations in your car's manual.

In cases where the engine has undergone significant wear and tear, such as from heavy use, mechanics often recommend switching to a higher-viscosity oil to compensate for the increased wear.

Can oils of different grades be mixed?

Mixing oils with different viscosities is not recommended during an oil change. However, in emergencies—such as when the oil level drops low enough to trigger a dashboard warning and the exact oil grade isn’t available—you can use an oil with a similar viscosity. For example:

• If your current oil is xW-30, you can add a small amount of xW-20 or xW-40 to restore the oil level without causing engine issues.

Nevertheless, when it’s time for your regular maintenance check, it’s essential to replace the oil entirely with the correct grade and investigate why the oil level dropped in the first place.

Caution

If you notice that your engine oil is depleting unusually fast, promptly refill it to the appropriate level. Running an engine with insufficient oil can cause severe damage, potentially requiring a complete engine replacement.

Read More:  Are Counterfeit Engine Oils Real? Here is How to Spot Them!

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