Difference Between 5w30 and 5w40

Synthetic oils, intended for more modern vehicles and engines, are by far the best option, as they differ from mineral and semi-synthetic oils in specific processing methods, characterized by excellent resistance to extremely low and high temperatures, and protect engine wear.

What is 5w30?

One of the common brands of oil in cars is SAE 5W30. SAE is an abbreviation for “Society of Automotive Engineers”, while the 5 and 30 markings are for the viscosity of the oil, i.e. the higher the number, the higher the viscosity of the oil. W indicates “winter”, that is, the properties of the oil at low temperatures. The purpose of a motor oil is to protect the vehicle’s engine in winter when temperatures are low or that the oil is light enough to run the engine without any difficulty on cold starts, and is thick enough to keep the engine running smoothly. engine running at the same level. Operating temperature. The goal is to reduce the viscosity of the oil at low temperatures and increase it at high temperatures. This allows the use of the same oil throughout the year. Oils that meet only summer or winter conditions are called single grade or mono grade oils. To obtain multigrade, i.e. more seasonal properties, it is necessary to add conventional additives to various base motor oil additives, for example SAE 5 base. These additives will reduce viscosity in cold engine operation, but will also increase viscosity. viscosity at engine operating temperatures. This product belongs to the category of universal lubricating oils and therefore has a large set of qualities. The substance is effective at a low temperature of -25 ° C. As for the high temperature threshold, it is 25 degrees. Many manufacturers test the quality of their cars in special booths. But all the same, the characteristics that the manufacturer puts on the packaging may be significantly different from what the substance will have during intensive work in the internal combustion engine. In this regard, both car dealers and motorists conduct their own oil test in working conditions. The tests are designed to show over what period of time the product loses its traits.

What is 5w40?

To achieve more economical driving, US engineers have introduced a series of parameters that provide the correct combination of certain SAE 5w40 viscosity oils to generate energy savings. It is essential to reduce oil consumption by 1.5%. In European practice (ACEA, ILSAC) this value exceeds a minimum value of 2.5%.

Main differences in quality of SAE 5w40:

  • Easy start at low temperature.
  • High oxidation stability.
  • Longer replacement interval
  • Oil film stability
  • Good detergent properties.
SAE 5w40 specs and reviews:
  • Minimal engine contamination.
  • Increased life due to better antioxidant properties.
  • Reduced friction in cold weather when starting the power unit
  • Resistance to evaporation (savings in filling)
  • Reduces engine wear due to simple flow of synthetic SAE 5w40 oil at low temperatures

5W – means keep the oil flow at low temperature – 35 ° C. The starting point is 40 ° C (5-40 = 35). Due to this property, the engine will not run “dry” in frost, but the oil will penetrate into all important components, and the life of the engine will last.

40 – generalized viscosity index at high temperatures up to 150 ° C. The thickness of the oil, first of all, depends on the size of this figure.

Difference between 5w30 and 5w40

Low shear rate viscosity for 5w30 and 5w40

The working viscosity of 40 is from 12.5 to 16.3 mm.two/ s 100g. The operating viscosity of 30 is 9.3 to 12.5 mm.two/ s 100g. Both oils are grade 5 when cold, but 5w30 is grade 30 and 5w40 is grade 40 at operating temperatures. 5w40 with higher temperatures in summer has a higher viscosity than 5w30, which contributes to the uninterrupted operation of the engine.

High shear rate viscosity

For a working viscosity of 40, this parameter is 3.5 min at 150 g. For a working viscosity of 30, this parameter must be at least 2.9 at 150 g. To a large extent, this indicator gives an idea of ​​​​how much the oil sustains under extreme loads.

Temperature range for 5w30 and 5w40.

5w30 is used in temperature ranges from -25°C to 25°C, while 5w40 from -25°C to 35°C.

Oil flow

5w40 provides higher pressure but less flow.

Thickness of 5w30 and 5w40.

5W30 is lighter, so it got better fuel consumption.

Fuel economy

5w40 has poorer fuel economy.


5w30 can be used by different types of vehicles and in different temperature ranges, but is ideal for cooler temperatures. 5w40 is often used in higher mileage engines, grit performs better in warmer temps.


5w30 is usually more expensive.

Summary of 5w30 vs. 5w40

  • 5w30 oil is designed to work in temperatures as low as -25°C, but is also a great option for warmer climates reaching 25°C. Overall, 5w30 is a great multigrade oil for different temperature spectrums. It is also more efficient in fuel consumption.
  • 5W40 is a motor oil that penetrates the active mechanisms faster and provides excellent lubrication at start-up. The number “40” implies that it differs from the more common motor oil (30) found in cars, as it is thicker , and this ensures deeper engine lubrication during high temperatures. This oil is most often used for higher mileage vehicles as it is thicker than 30 oil so it will provide better lubrication for working parts within the engine that have worn due to aging or the tension.

Leave a Comment