Updated at: 23-07-2022 - By: Lucas

If you want to keep your car’s internal combustion engine in good working order, you must change the oil on a regular basis and at specific mileages. However, because there are so many different kinds of engine oil, drivers are continually trying to figure out what the distinctions are and what oil is best for their particular engine.

The SAE standards


The Society of Automotive Engineers, or SAE, classifies motor oil according on its viscosity. International recognition of this European organization’s high quality standards and guidelines dates back many years. Efforts are being made by all lubricant manufacturers to meet these requirements.

Every engine oil tank you buy has the SAE mark on it. The following is what it means:

  • the number in front of the letter “w”, an abbreviation for “winter”, that indicates at what minimum temperature the oil retains its fluidity for the winter;
  • the number after the letter “w” displays the maximum possible temperature at which the oil can be applied without worrying that it will no longer cope with the loads due to excessive fluidity.

Many oil properties are covered under SAE standards. Here we’ll focus on just a few of the most important:

  • Kinematic viscosity. The ratio of the dynamic viscosity to the density of the lubricating component;
  • Starting properties. Determine what resistance is created by the liquid when the cooled engine is activated, and also whether it is possible to reach the speed required for start at a certain ambient temperature;
  • The degree of pumping. The speed of oil delivery to the rubbing parts of the engine during a cold start;
  • Viscosity at high temperatures. Measured during excessive loads on the car’s motor.

SAE markings are difficult for novice drivers to decipher. A lubricant may appear to only work at a certain temperature if there is a 0 in front of the w, but this is not the case. In reality, things have changed somewhat.

You may find out more about engine oil qualities by visiting this page.

Here, oil viscosity at low temperatures is an issue.

It is safe to use 0w engine oil in temperatures up to 35 °C or 31 °F throughout the winter.

When it comes to high-temperature viscosity:

  • 0w30 oil can do great at high temperatures up to 35 °С or 86°F
  • 0w40 oil can do its job well at high temperatures up to 40 °С or 104°F

Differences between 0w30 and 0w40 engine oils


In general, both are universal all-season oils that need to be changed once a year or every 9000-15000 kilometers or every 5600-9300 miles.

Both oils are 0w products and can be used at temperatures as low as 35 °Cup to 40 °C (31 °F up to 40 °F) or even lower, depending on the nature of the oil.

The fluidity at the engine operating temperature will be significantly different because of their differing upper ranges.

The indication for 0W40 oil should read between 12. 5 and 16. 2 mm2/s while operating at a temperature of 100 °C (212 °F). 0W40 oil is thicker and forms a denser layer on the engine walls than 0W30, according to this indicator.

In the winter, both 0w 30 and 0w 40 oils are suitable because the temperature variation is limited but can have a significant impact on the engine overall, especially at higher temperatures. They will perform their job.

It was determined that 0w30 and 0w40 motor oils have different properties. Consequently, when comparing the two types of oil made by the same company, the difference was clearly evident.

Because of its high viscosity, 0w40 motor oil is the most difficult to turn the crankshaft in. At 30 °C or 22 °F, the slightly less versatile 0w30 was found to be 9 percent less viscous than the 0w20.

The two viscosities may appear to be the same to most drivers, yet opinions are varied. Common misconceptions about 0w30 oil include its lighter weight than 0w40 and its superior low-temperature flowability. Therefore, it’s most suited for vehicles that don’t encounter large snowfalls or freezing temperatures on a regular basis.

All weather situations and vehicles with higher horsepower engines can benefit from using 0w40 oil, as the friction inside the engine increases when the engine temperature is cold, necessitating additional lubrication for the protection of engine parts.

When it comes to high temperatures, the differences between 0w30 and 0w40 motor oil aren’t all that noticeable. High temperatures are no problem for 0w40 oil, which functions admirably even at temperatures as high as 100 °F (37 °C).

After driving in hot conditions for several days, test subjects found that 0w40 oil was smooth and didn’t build up on the inside of their engines.


In the winter, 0w30 and 0w40 motor oils are ideal for use since they have greater viscosities that allow them to perform more effectively at lower temperatures.

In extremely frigid temperatures, 0w40 motor oil offers a modest benefit. Because of the oil’s great performance in hot temperatures, your car’s engine runs more efficiently in the summer because of the reduced friction that occurs when the temperature rises within the usual operating range.