5w40 vs 10w40

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Picking the right motor oil is quite crucial for you to keep your vehicle engines lively. Currently, the two best picks among the motor oils are 5w40 and 10w40.

They are appropriate in terms of viscosity and other specifications to ensure that your vehicle engine is free from all types of critical damage. However, to make the right choice between these two oils, you need to know their differences.

5w40 vs 10w40

Even though both of these oils are used alternatingly, but they still do have some differences. And, these differences in their thickness, weight, and viscosity determine their usage.

Hence, if you are in a dilemma to choose one among these two oils, then this 5w40 vs 10w40 article will provide you with the required information.

5w40 Specifications

5w40 is a very thin engine oil, preferable for most heavy-duty engines. The design and blend of this oil are ideal for reaching out to the engine’s moving parts smoothly after the initial start-up.

The viscosity grade of the lube oils, such as 5w40, is determined by SAE (Society of Automotive Engineers). These oils are categorized into monograde and multi-grade oils for use in different vehicles. 5w40 is a multi-grade oil meant mostly for modern engines.

An oil container of an 5w40 motor oil

The numbers denoted for 5w40 oil represent its viscosity in low and operating temperatures. Thus, the number ‘5’ represents the viscosity of this oil at low temperatures.

And, the number ’40’ represents the viscosity of the engine oil in operating or high temperatures. Thus, it is more like a rating that indicates the thickness, weight, and viscosity of the oil altogether.

The mechanics and automobile manufacturers prefer to use 5w40 for the engines that produce high mileage. The reason behind it is that this oil is usually thick in comparison to most of the other oil types. Also, it is more heat resistant than any average oil type.

Therefore, for all the vehicles operating in cold climates, 5w40 is an ideal pick, as a cold engine pump is more effective with this oil. Moreover, it can give a stable pump to the engine, even at the lowest temperature of -30 degrees Celsius.

10w40 Specifications

In comparison to 5w40, 10w40 is a thicker oil. However, it is thin in comparison to other oil types available in the market.

Furthermore, the older vehicle engines require special oil to revive their functionality and enhance their performance optimally. Therefore, this motor oil is quite perfect in terms of lubrication for the older parts.

This oil supports engine start-up in cold climates but is not reliable in comparison to 5w40. It is because the efficiency of this oil is to operate only up to -20 degrees Celsius.

Therefore, it is an optimal efficacy of this motor oil. But still, it is less reliable in more extreme climatic conditions

Breaking down by the number, 10w40 has a thickness, weight, and viscosity rating of ’10’ for low temperatures. And, it has a rating of ’40’ at high or operating temperatures. Hence, it proves that the oil is thicker than most other average oils in the market.

When engines turn hot, this oil turns thicker! Hence, it helps the vehicle engine to pump up sufficiently to get that initial boost. However, it is not much significant in terms of fuel economy due to its highly viscous nature.

5w40 vs 10w40


  • Both of the oils have the same operating temperature viscosity rating of ’40’.
  • Both of these oils are preferable and essential for motorcycle engines as well.
  • Thickness is the same for both these oils at high temperatures, as they possess the same viscosity.
  • Both oils work well in greasing the engine parts proficiently.


  • 10w40 is thick oil in comparison to 5w40 at low temperatures.
  • 10w40 is ideal to operate at the lowest temperature of -20 degrees Celsius, whereas 5w40 can operate at -30 degrees Celsius.
  • 5w40 has a smoother flow in comparison to 10w40.
  • Also, 5w40 is termed to be more fuel-efficient motor oil than 10w40.
  • 5w40 is mostly preferable for modern engines, whereas 10w40 can be picked for older vehicle engines.

Major Distinguishing Factor

The major distinguishing factor between these oils is the operating viscosity. For example, the operating viscosity of 5w40 ranges from 3.8 to 12.5 mm2/s, whereas for 10w40, it is 4.1 to 12.5 mm2/s.

Oil being poured on a gold surface

When to Use 5w40?

You should use the 5w40 oil when you mostly intend to support high-mileage engines. It is because this oil is thick and has better heat resistance in comparison to ordinary oils. To quickly distinguish the similar products, check out the properties of 5w20 and 5w30, as well.

In addition, timely lubrication is important for the modern engine parts that wear out over time. Therefore, 5w40 is the perfect pick for modern engines, as the top manufacturers recommend the same. Moreover, 5w40 is also a perfect motor oil for vehicles running in colder climates.

When to Use 10w40?

You should use 10w40 motor oil, mostly in the old vehicles. As old vehicle engines require robust lubrication, this is an ideal pick. But, again, this is best for hot climates or for vehicles that frequently commute long distances.

Final Verdict

For choosing the best oil between 5w40 and 10w40, you need to first go through the manufacturer’s instructions of your vehicle to check what oil is suitable for the same. Both the oils have near about the same specifications, with minor differences. Therefore, you must consider the temperature and viscosity factor on priority to decide the best one as per your necessity.