Can I Use 10W30 Instead of 5W20? Impacts of Oil Viscosity

Regarding vehicle maintenance, one of the most frequently asked questions is whether it’s acceptable to use a different type of motor oil than the manufacturer’s recommendation. Specifically, can I use 10W30 instead of 5W20? This question arises often due to availability issues or sometimes simple curiosity. To answer this question adequately, it’s crucial to explore 10w30 vs 5w20 motor oil, their viscosity ratings, and how those affect your engine’s performance and longevity.

can you use 10w30 instead of 5w20

Can I Use 10w30 Instead of 5w20?

Manufacturer’s Recommendations

Vehicle manufacturers spend millions in R&D to find the optimal motor oil that provides the best protection, longevity, and fuel economy for your specific engine. These recommendations are stated in the owner’s manual and are there for a reason. Deviating from these recommendations could result in decreased engine efficiency, increased wear, and may even void your vehicle’s warranty. Here’s a breakdown of potential effects if you use 10w30 instead of 5w20:

The Risks Involved

Changing 10W30 oil instead of 5W20 might seem like a minor adjustment, but there are several risks involved:

  1. Increased Wear and Tear: The higher viscosity oil (10W30) may not flow as easily through the engine as the recommended 5W20, especially at cold starts. This can lead to inadequate lubrication, resulting in higher wear and tear on the engine.
  2. Reduced Fuel Efficiency: Higher viscosity oils are generally less efficient at reducing friction, which could result in reduced fuel efficiency.
  3. Voiding Warranty: Some manufacturers specify that using a different type of oil can void the vehicle’s warranty, particularly if the engine suffers damage that can be traced back to the use of the incorrect oil type.

Special Circumstances

  1. Emergency Situations: In an emergency, it’s better to have some oil rather than none. Using 10W30 temporarily won’t catastrophically damage your engine, but switching back to the recommended 5W20 is advisable as soon as possible.
  2. Climate Considerations: Different oil types may be more appropriate in extremely cold or hot climates. Consult local experts in these situations.
  3. High-Mileage Engines: Older engines sometimes benefit from higher viscosity oils, but this should be discussed with a qualified mechanic familiar with your engine’s specific needs.

What is the Difference Between 5W-20 and 10W-30?

The difference between 5W-20 and 10W-30 motor oils lies primarily in their viscosity ratings at various temperatures. The numbers and letters in these designations help describe the oil’s performance characteristics.

10w30 vs 5w20

Understanding the Nomenclature of 5w20 vs 10w30

  • 5W-20: The ‘5W’ denotes that the oil has a viscosity rating of 5 in cold temperatures (‘W’ stands for winter). The ’20’ refers to the viscosity of the oil at the engine’s normal operating temperature.
  • 10W-30: In this case, ’10W’ means that the oil has a slightly higher viscosity rating of 10 when cold. The ’30’ indicates a higher viscosity at normal operating temperature than 5W-20.

What Does This Mean Practically?

  1. Cold Temperature Performance: A 5W-20 oil will flow more easily at lower temperatures compared to a 10W-30 oil. This makes 5W-20 preferable for colder climates or for engines that require rapid lubrication upon start-up.
  2. High Temperature Performance: The 10W-30 oil maintains a higher viscosity at higher temperatures compared to 5W-20. This can be beneficial in higher heat conditions or for engines that operate at higher temperatures.
  3. Fuel Efficiency: Lower viscosity oils generally offer better fuel efficiency. Therefore, 5W-20 oils may provide slightly better fuel economy compared to 10W-30 oils.
  4. Engine Wear: At higher temperatures, the 10W-30 oil will be thicker than 5W-20, which may offer better protection against wear in some high-stress or high-temperature conditions. However, it’s worth noting that most modern engines are designed for lower viscosity oils like 5W-20 to meet efficiency and emissions standards.
  5. Manufacturer’s Recommendation: Always consider what the vehicle’s manufacturer recommends. Using the wrong type of oil can lead to decreased performance, increased engine wear, and may even void your warranty.
  6. Climate: In warmer climates, the higher high-temperature viscosity of 10W-30 may be advantageous. Conversely, the lower cold-temperature viscosity of 5W-20 could be beneficial in colder climates.
  7. Compatibility: Some older engines might benefit from higher viscosity oils like 10W-30, but it’s best to consult a mechanic for advice tailored to your specific engine.

In summary, while both 5W-20 and 10W-30 are multi-viscosity oils designed to operate in a range of temperatures, they have different performance characteristics that make them suited for different applications and conditions. Refer to your vehicle’s owner’s manual for the manufacturer’s recommended oil type.

Can You Mix 10w30 and 5w20?

Yes, you can mix 10w30 and 5w20. However, mixing different types of motor oils is generally not recommended because each oil type has been specifically formulated to provide certain characteristics such as viscosity, detergency, and heat dissipation. However, if you’re in an emergency situation where you have no other option, mixing 10W30 and 5W20 is better than running your vehicle with a low oil level.

Here’s what you need to consider:


  • When you mix 10W30 and 5W20, you are effectively averaging their viscosities, although not perfectly. The resulting mixture will have a viscosity that falls between the two.


  • It is important to ensure that both the 10W30 and 5W20 oils meet the specifications set forth by your vehicle’s manufacturer. This usually means checking for the relevant API service classifications and other certifications on the label.

Short-Term vs Long-Term:

  • If you have to mix oils as a temporary measure, aim to change the oil completely at the earliest opportunity. Running mixed oils over the long term is not advisable due to unpredictable characteristics like viscosity, wear protection, and heat dissipation.


  • Mixing different types of oil could void your vehicle’s warranty, particularly if engine damage can be traced back to the use of incorrect or mixed types of oil.


  • Different oil formulations contain different additives (detergents, anti-wear additives, etc.), which may not be fully compatible when mixed. This could lead to less effective lubrication and wear protection.

When it’s OK:

  • For older, high-mileage engines that are out of warranty and not in tip-top shape, mixing oils in a pinch is less of a concern, though still not ideal.

Professional Advice:

  • Whenever possible, consult with a mechanic or other experts before mixing the different oils to understand the implications for your specific vehicle.

When Should You Use 5W-20 oil?

The use of 5W-20 oil is primarily determined by your vehicle’s manufacturer’s guidelines, typically found in the owner’s manual. This low-viscosity oil is often recommended for modern engines designed for better fuel efficiency and reduced emissions. The “5W” signifies good low-temperature performance, making this oil suitable for cold climates where quick oil flow at startup is crucial for engine protection.

Additionally, 5W-20 oil generally improves fuel economy due to reduced internal engine friction. It’s commonly recommended for everyday driving conditions—such as commuting or city driving—rather than extreme situations like heavy towing or high-temperature operations. The recommended oil amount is especially important for vehicles under warranty to avoid voiding the coverage. Always consult your vehicle’s manual to ensure you use the appropriate oil for optimal engine performance and longevity.

Is 10W-30 Good in Hot Weather?

Yes, 10W-30 oil is generally well-suited for hot weather conditions. The “30” in 10W-30 indicates that the oil maintains a thicker viscosity at higher operating temperatures than lower-viscosity oils like 5W-20. This thicker film of oil provides better protection against wear and tear, especially when the engine is subjected to high levels of stress or heat.

In hotter climates, the higher high-temperature viscosity can offer advantages, such as reduced oil thinning and improved engine protection under thermal stress. If you’re in a region where temperatures frequently soar, or your vehicle experiences high-stress conditions like towing or extended idling, 10W-30 can be a good choice. However, it’s essential to consult your vehicle’s owner’s manual or a qualified mechanic for specific recommendations, as using a non-recommended oil could void your warranty or negatively affect engine performance.Top of Form


Can I use 10w30 instead of 5w20? It’s generally best to stick with your vehicle manufacturer’s recommendations. The risks involved in deviating from these guidelines usually outweigh any perceived benefits. However, a temporary change could be considered in emergencies or special circumstances like extreme climate or high-mileage engines, preferably after consulting a qualified mechanic. Always remember, it’s better to be safe than sorry when it comes to your vehicle.


Mr. Shafiqule Islam is a graduated Mechanical Engineer and has more than 15 years experience of repairing and maintenance of different brand vehicles like Toyota, Mitsubishi, Ford, Mercedes, BMW etc. He is also giving training to Mechanics. He has started writing to share his practical knowledge to Vehicle Owners, Drivers and Mechanics to keep their cars at best fit.

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