Difference between 5w30 and 5w40

Synthetic oils for more modern vehicles and engines are by far the best choice because they are different from mineral and semi-synthetic oils in specific processing methods and are characterized by excellent resistance and Protect engine wear. 

What is 5w30?

One of the common oil marks in cars is SAE 5W30. SAE is an acronym for "Society of Automotive Engineers", and 5 and 30 are marked as oil viscosity, ie the higher the number, the higher the oil viscosity. W stands for "winter", the properties of oil at low temperatures. 

The goal of the oil is to protect the vehicle's engine during low winter temperatures, or the oil is light enough so that the engine doesn't have any trouble with a cold start and is dense enough to keep the engine running at the same operating temperature. 

The purpose is to reduce the viscosity of the oil at low temperatures and increase it at high temperatures. This allows the same oil to be used throughout the year. Oils that meet only summer or winter conditions are called monograde or monograde oils. 

In order to obtain multi-grade, ie more seasonal characteristics, conventional additives need to be added to various engine oil base additives such as SAE 5 base. 

These additives reduce the viscosity of the engine when it is cold running, but also increase the viscosity at the engine operating temperature. This product belongs to the general-purpose lubricant category and therefore has a variety of qualities. 

The substance is effective at low temperatures of -25°C. As for the high-temperature threshold, it is 25 degrees. Many manufacturers test the quality of their cars at special booths. 

But in any case, the manufacturer's properties on the packaging may be very different from the properties the substance has during the intensive operation of the internal combustion engine. 

In these regards, car dealers as well as motorists conduct their own oil tests under working conditions.

What is 5w40?

To achieve a more economical ride, American engineers have introduced a number of parameters that allow the correct combination of certain SAE 5w40 viscosity oils to save energy. It is imperative to reduce fuel consumption by 1.5%. In European practice (ACEA, ILSAC), this value exceeds the minimum value of 2.5%.

Key differences in SAE 5w40 quality:

  • Easy to start at a low temperature
  • High oxidative stability
  • Increased replacement interval
  • Oil film stability
  • good detergent performance


SAE 5w40 Specs and Reviews:

  • minimal engine pollution
  • Improve anti-oxidation performance and prolong the service life
  • Reduced cold weather friction when starting the powerplant
  • Evaporation resistance (saving filling)
  • Reduced engine wear due to the simple flow of synthetic oil SAE 5w40 at low temperatures


5W – means keeping oil flow at a low temperature of – 35°C. The starting point is 40°C (5-40 = 35). Thanks to this feature, the engine will not work "dry" under frost, but the oil will penetrate all vital components and the life of the engine will last.

40 – Generalized Viscosity Index at high temperatures up to 150°C. First, the thickness of the oil depends on the size of this number.


Difference between 5w30 and 5w40

1. Low Shear Rate Viscosity for 5w30 and 5w40

The working viscosity of the 40 is 12.5 to 16.3 mm  2 /s at 100 g. The 30 has an operating viscosity of 9.3 to 12.5 mm  2 /s at 100 g. Both oils are grade 5 when cold, but 5w30 is grade 30 and 5w40 is grade 40 at operating temperature. 5w40 with higher summer temperatures has a higher viscosity than 5w30, which helps the motor run uninterrupted

2. High Shear Rate Viscosity

For a working viscosity of 40, this parameter is a minimum of 3.5 at 150g. For a working viscosity of 30, this parameter should be at least 2.9 at 150g. To a large extent, this metric gives an idea of ​​how well the oil will withstand extreme loads.

3. Temperature range for 5w30 and 5w40

5w30 is used in the temperature range of -25°C to 25°C, while 5w40 is used in the temperature range of -25°C to 35°C.

4. oil flow

5w40 provides higher pressure but less flow.

5. Thickness of 5w30 and 5w40

The 5W30 is lighter and has better fuel consumption.

6. fuel economy

The 5w40 has poor fuel economy.

7. application

5w30 can be used in different types of vehicles and in different temperature ranges but is perfect for cooler temperatures. 5w40 is often used in higher mileage engine sands that perform better in warmer temperatures.

8. cost

5w30 is usually more expensive.


5w30 and 5w40 Comparison Summary

5w30 oil is designed to operate in temperatures as low as -25°C but is also an excellent choice for warm climates up to 25°C. Overall, 5w30 is an excellent multigrade oil for different temperature ranges. It is also more fuel efficient.

5W40 is an oil that penetrates faster into the active mechanism and provides excellent lubrication at startup. 

The number "40" means it is different from the most common motor oil (30) in cars because it is denser, which ensures deeper engine lubrication at high temperatures. 

This oil is most commonly used in higher mileage vehicles because it is thicker than 30 oil and therefore provides better lubrication for the working parts inside the motor that are worn from age or strain.

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