Can You Mix 10w30 and 5w30?

Motor oil is a vital component of any engine, ensuring its smooth operation and longevity. When it comes to choosing the right motor oil for your vehicle, you may come across different grades and types. One common question that arises is whether it is safe to mix different oil grades, such as 10w30 and 5w30. In this article, we will explore the compatibility of these two motor oils and shed light on the considerations for mixing them.

Understanding Motor Oil Grades

The grade of motor oil refers to its viscosity, which indicates its flow and thickness at different temperatures. The Society of Automotive Engineers (SAE) has established a standardized grading system to help consumers select the appropriate motor oil for their vehicles.

The viscosity grade is denoted by a combination of two numbers, such as 5w30 or 10w30. The “w” stands for winter, and the number preceding it represents the oil’s viscosity in cold temperatures, while the number after the “w” represents the viscosity at high temperatures. In simpler terms, the first number indicates how the oil flows in cold weather, while the second number indicates its flow in hot weather.

Exploring 10w30 and 5w30 Motor Oils

Both 10w30 and 5w30 motor oils are commonly used in various vehicles. Let’s take a closer look at each grade:

10w30 Motor Oil

10w30 motor oil has a viscosity rating of 10 at cold temperatures and 30 at high temperatures. It provides better protection in warmer climates and is suitable for older engines or those operating in hotter conditions. The higher viscosity of 10w30 oil ensures better lubrication and helps reduce engine wear.

5w30 Motor Oil

On the other hand, 5w30 motor oil has a lower viscosity rating of 5 at cold temperatures and 30 at high temperatures. It flows more easily in cold weather, allowing for quicker lubrication during startup. This grade of oil is commonly recommended for newer engines and colder climates.

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Can You Mix 10w30 and 5w30?

Now, let’s address the question at hand: can you mix 10w30 and 5w30 motor oils? The answer is yes. Mixing these two oils is safe and will not cause any harm to your engine. The reason behind this is that both oils have the same grade viscosity at high temperatures (30), making them compatible for combining.

While 10w30 is slightly denser than 5w30, the difference is not significant enough to cause any adverse effects. In fact, mixing the two oils can provide a balance between cold-weather flow and high-temperature lubrication. This is particularly beneficial in regions with fluctuating climates.

However, it is important to note that some vehicles may have specific requirements regarding motor oils. It’s always best to consult your vehicle’s manual or contact the manufacturer to determine the recommended oil grade. If your vehicle manual specifies using either 5w30 or 10w30 exclusively, it is advisable to stick to that recommendation to ensure optimal performance.

Considerations for Mixing Motor Oils

While mixing 10w30 and 5w30 motor oils is generally safe, there are a few considerations to keep in mind:

  1. Compatibility: Ensure that the motor oils you are mixing are compatible with each other. In the case of 10w30 and 5w30, their similar viscosity grades make them compatible for mixing.
  2. Quality and Condition: It is essential to use high-quality oils from reputable brands. Additionally, ensure that both oils are in good condition and not contaminated. Mixing contaminated or degraded oils can have negative effects on engine performance.
  3. Proportions: When mixing oils, it is recommended to maintain a relatively equal ratio between the two grades. This helps maintain the desired viscosity and lubrication properties.

How to mix 5w30 with 10w30?

To mix 5w30 with 10w30 motor oils, follow these steps:

  1. Gather the necessary materials: You will need a clean and empty container to mix the oils, such as a measuring cup or an oil drain pan.
  2. Ensure cleanliness: Make sure the container you are using is clean and free from any contaminants. Even small amounts of dirt or debris can negatively affect the performance of the mixed oil.
  3. Check the proportions: It is generally recommended to maintain a relatively equal ratio between the two oils. For example, you can mix equal parts of 5w30 and 10w30 oils, such as 50% of each. This will help maintain the desired viscosity and lubrication properties.
  4. Pour the oils: Carefully pour the 5w30 and 10w30 oils into the clean container, following the desired ratio. Use a funnel if needed to prevent spillage.
  5. Mix thoroughly: Once the oils are in the container, use a clean stirrer or stick to mix them thoroughly. Ensure that both oils are well blended to create a homogeneous mixture.
  6. Transfer the mixed oil: Once the oils are mixed, you can transfer the resulting blend back into the original oil containers or use a separate container for storage. Make sure the storage container is tightly sealed to prevent any contaminants from entering.
  7. Label the container: It is essential to label the container with the type of oil mixture and the date it was mixed. This will help you keep track of the oil blend and ensure you use it within the recommended timeframe.
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Remember, while mixing 5w30 with 10w30 is generally safe, it’s always advisable to consult your vehicle’s manual or contact the manufacturer for any specific instructions or recommendations regarding oil mixing.

Following Manufacturer Recommendations

While mixing 10w30 and 5w30 motor oils may be acceptable in most cases, it is crucial to consider the manufacturer’s recommendations for your specific vehicle. Manufacturers spend extensive time and resources testing different oils to determine the best match for their engines. Therefore, it is wise to follow their recommendations to ensure optimal performance, longevity, and warranty coverage.


In conclusion, you can safely mix 5w30 with 10w30 motor oils. Both oils have the same grade viscosity at high temperatures, making them compatible for combining. Mixing them can provide a balanced solution for different temperature conditions. However, it is always advisable to refer to your vehicle’s manual or consult the manufacturer for specific oil recommendations. By following these guidelines, you can ensure the longevity and optimal performance of your engine.


Q: Can I mix synthetic 10w30 with conventional 5w30 oil?

A: Yes, you can safely mix synthetic 10w30 with conventional 5w30 oil. Synthetic and conventional oils are compatible, and blending them won’t cause any harm to your engine. However, keep in mind that the resulting blend will have properties similar to that of conventional oil.

Q: Can I mix different brands of 10w30 and 5w30 oils?

A: Yes, you can mix different brands of 10w30 and 5w30 oils. As long as the oils have similar viscosity grades, they can be safely combined. However, using high-quality oils from reputable brands is recommended for optimal performance.

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Q: Is it better to stick to a single oil grade instead of mixing?

A: If your vehicle’s manufacturer recommends using only one oil grade, it’s best to stick to their recommendation. Manufacturers consider various factors when determining the optimal oil for their engines, and deviating from their guidelines may affect performance and warranty coverage.

Q: Can mixing oils improve fuel efficiency?

A: While mixing oils won’t directly improve fuel efficiency, using the correct oil grade recommended by the manufacturer can help optimize your vehicle’s performance, which in turn may positively impact fuel consumption.

Q: Can I mix 10w30 and 5w30 oils in my motorcycle?

A: It’s essential to consult your motorcycle’s owner’s manual or a qualified mechanic to determine the suitable oil grade for your specific motorcycle. Mixing oils in motorcycles may have different considerations compared to cars, so it’s best to follow the manufacturer’s recommendations.

Q: Can I mix 10w30 and 5w30 oils in extreme temperatures?

A: The blend of 10w30 and 5w30 oils can provide adequate protection in a wide range of temperatures. However, if you frequently operate your vehicle in extreme hot or cold conditions, it’s advisable to use an oil specifically formulated for those conditions.

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