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5w40 VS 15w40: Which Is Better? (Pros & Cons)

5w40 VS 15w40: Which Is Better? (Pros & Cons)

A vehicle is made up of a combination of many complex machines which work together to move. The maintenance of these machines is very essential to sustain the life of any vehicle.

There are many tools and components used to achieve the objective of maintaining the car. When thinking about components for maintenance of the car, engine oil is a thing that generally comes to the minds of many of us.

Engine oil is the most important lubricant for an engine to keep moving properly and smoothly.

As there are many types of engine oil present in the market that in some cases can mislead the driver and they may end up using an engine oil that is not suitable for their engine. Usage of the wrong engine oil can cause serious problems.

5w40 and 15w40 are two different types of engine oil that seem and sound similar.

15w40 is perfect to use in an environment where the temperature range from -20 Celsius to 40 Celsius. Whereas, 5w40 is used in temperatures ranging from -30 to 40 Celsius.

This is just one difference between 15w40 and 5w40, to know more differences and facts read till the end as I’ll be covering them all.

Overview of 5w40

5w40 is a multigrade type of engine oil that can be used in any season, it blends synthetic crude oil and petroleum. Its name refers to how well the oil type can help the engine regarding the ambient temperature in which they are used.

cars driving down the road
5W40 can be used for higher mileage engines and warmer temperatures.

The W means winter as it is classified using a conventional categorization system.

The number before W indicates oil viscosity or thickness at a lower temperature and the number after it indicates oil viscosity at a higher temperature (150-celsius average) while the engine is running.

5w40 can be used in the temperature range of -30 °C (-22°F) and +40 °C (104°F). We can say that 5w40 does a better job in a warmer environment. This oil is suitable for a car driven 15000 miles per year on regular basis.

What are the benefits of using 5w40 oil?

There are many pros and cons of using 5w40 oil which you know before getting the engine oil.


There are many benefits or pros of using 5w40 that would have a significant effect on your vehicle’s engine performance. Following are some advantages of using 5w40 oil:

  • Good cleaning from impurities.
  • Provides good heat resistance.
  • Can coup with aggressive driving style and extreme conditions.
  • Retains properties for longer, protecting the engine from wear.


These are some cons of using 5w40 oil that you must consider before choosing it for your vehicle.

  • Is more expensive than 15w40.
  • Not recommended by many manufacturers.
  • Can be used in engines that are not worn out.

Overview of 15w40

Engine oil with the designation of 15w40 is a multigrade oil that has good flow properties at both cold and warm temperatures. The name 15w40 refers to SAE according to which engine oils are classified. 15W indicates flowability at low temperature and W stands for winter. Number 40 describes flowability at high temperature of around 100 °C.

The kinematic viscosity of 15W40 oil operating at 100 °C is in the range of 12.5 to 16.2 mm²/s. The cold resistance for 15W40 is roughly -20 °C or -4 °F. 15w40 is perfect to use in an environment where the temperature range from -20 Celsius to 40 Celsius.

It is all-season use lubricant that can be used in both cold and warm temperatures. 15W40 oil type is ideal with worn engines as it avoids corrosive activities and encourages clearance of sludge. Although 15w40 lubricant can be used in all seasons, it’s good for engines in hot climates.

If you want a more comprehensive discussion on how 15W40 engine oil can be good for your car, check this video out.

A video explaining the usage of 15W40 engine oil.

Advantages and drawbacks of using 15w40 oil

engine oil being poured into a car
Even at greater ambient temperatures, the lubricant flows quicker through the engine than pure SAE 40.

Like everything 15w40 engine oil type also has some pros and cons. These pros and cons are essential for a person to know before choosing engine oil for his vehicle.


There are many pros of using it 15w40, some of them are mentioned below:

  • It is cheaper to produce.
  • Suits well with the worn-out engines as it protects the engine better.
  • Good for engines operating in a warmer climate.
  • Promotes removal of sludges.
  • Prevents the formation of corrosive processes.


With many advantages, there are some disadvantages of using the 15w40 oil type as well which need to be considered before choosing engine oil for your vehicle. Following are some cons of using the 15w40 oil type.

  • Although 15w40 oil type can be used in all seasons. However, it’s not the best option at low temperatures below -20 Celsius or -4 degrees Fahrenheit.
  • 15w40 oil type is unable to maintain viscosity in extreme operating conditions and during a more aggressive style of driving.

Is 5w40 and 15w40 the same?

Although both engines oils 5w40 and 15w40 are multigrade oils and are quite similar by name, they are different from each other in many ways. The table below represents the major difference between the two engine oil types.

Preferred climate conditionsWarmCold
ProsCheaper to produce and suits well with the worn-out engines.Helps the engine in a colder environment especially while starting and has good heat resistance.
ConsNot a good choice in cold temperatures less than -20 Celsius, losses viscosity while operating in extreme conditions.More expensive than 15w40, some manufacturers do not recommend it.
Range of Temperature to Operate-20 Celsius to 40 Celsius.-30 to 40 Celsius.
Major differences between 5w40 and 15w40 engine oil.

5w40 vs. 15w40: Which one is better?

engine oil being poured into a funnel
5W-40 is easier to start and lubricates faster than 15W-40 in the cold.

5w40 and 15w40 are two different oil types with their own usage advantage and disadvantages. You might be thinking which one of the oil types is better?

Both 5w40 and 15w40 have their own specifications and usage conditions which make this answer a bit tricky to answer.

No doubt 5w40 is way better than 15w40 as it allows a quick start and works properly even with an aggressive driving style.

But still, it’s not an ideal choice in cold temperatures as it loses its property below -20 degrees celsius. So, 15w40 can be a good choice for those who are living in a very cold area as it provides more effective stability in low temperatures.

Can I mix 15w40 with 5w40?

You can mix 15×40 with 5w40, there is no problem but it is not recommended and advisable for everyone.

What can happen by mixing both lubricants is that your vehicle warranty can be voided. If your vehicle is out of warranty, then you can try mixing 15w40 and 5w40 oil.

But one thing to remember is that it is risky to mix two different types of oil.


5w40 and 15w40 are two different types of oils that have different usage conditions, advantages, and disadvantages.

When choosing engine oil whether it be 15w40 or 5w40, you must choose engine oil that suits perfectly your vehicle’s performance and you must also temperature at which the vehicle would operate.

No matter if you buy 15w40 or 5w40 it’s useless if it’s not manufactured by any trustworthy company or brand. Using engine oil of low quality and standard can create many new problems for you as well, so must not compromise on the quality and standard of the oil.

Other Articles

A web story that differentiates these two engine oils can be found here.

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