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0w-40 Vs 5w-30 (What’s The Difference?)

If you have ever gotten the oil changed in your car, you may have wondered why there are so many motor/engine oil options and what’s the difference between them all.

To clear some confusion, today, we will look at two similar types of motor oils – 0w-40 and 5w-30 – to give you a comprehensive comparison between the two. You will learn their subtle differences and, consequently, some of the things that make them similar.

What Is Motor/ Engine Oil?

Motor oil is a lubricant made with base oil and additives such as friction modifiers, antioxidants, detergents and more. It helps cars, bikes, lawnmowers, and other machines to reduce friction in their combustion engines, or “motors”, and work smoothly to produce power.

There are three main types of motor/ engine oils.

  1. Synthetic Oils: The most commonly used variants because they have been modified to work in a wide range of temperatures, keep the engine clean, and offer superior fuel economy.
  2. Semi-Synthetic Oils: These are a hybrid variant between synthetic and mineral oils.
  3. Mineral Oils: The least expensive of all, these oils are not recommended for cars, especially newer cars, because of their lack of detergents for cleaning the engine.

Now that we have a better understanding of motor/ engine oils, let’s dive deeper into 0w-40 and 5w-30, to understand the difference between the two.

0w-40 Vs 5w-30 (What’s The Difference?)

There are a few key differences between 0w-40 and 5w-30, including their oil grade, viscosity, temperature range, and fuel efficiency.

Grading and Viscosity

Viscosity in motor/ engine oils refers to the flow of the oil and how thick or thin it is. You can think of thick oil’s consistency being like ketchup, while thin oil is like a beer; ketchup is relatively thicker and more viscous than beer.

The first number in the name of the motor/ engine oil refers to its grading or viscosity. There are two types of grades in oils. Single-grades can be either thick or thin, whereas multi-grades are thick and thin. The viscosity of single-grade oils is represented by a single digit.

On the other hand, the viscosity of multi-grade oils is represented by two digits with an alphabet in the middle to represent the temperature.

In the case of 0w-40 and 5w-30, the W tells us that these are motor/ engine oils designed for winters. The number before the W tells us the weight or level of viscosity at low temperatures. We can differentiate the two as the higher this number is, the thicker the oil.

Following this, we can tell that 0w-40 is thinner than 5w-30, which has a higher viscosity of 5. The number after the alphabet tells us the viscosity of the oil at the normal temperature of a running engine, typically measured at 100°C.

0w40 is, therefore, a thinner oil that must drop within a higher viscosity limit of 40, at 100°C. Whereas 5w30 is a thicker oil that must drop within a lower viscosity limit of 30, at 100°C. Both these oils are represented by two digits with an alphabet in the middle, offering a wide range of temperatures where the oil can be thick and thin.

Therefore, they are both multi-grade motor/ engine oils. In comparison, a single-grade motor/ engine oil may be named SAE 20W, which means it is a winter oil that holds a single viscosity level. However, as time passes, such single-grade oils are becoming outdated.

Fuel Efficiency

The type of oil used in a combustion engine affects the fuel efficiency or consumption of the engine. For example, mineral oil in engines will lead to a car consuming more gas than a car that uses synthetic oil in its engine.

Both 0w-40 and 5w-30 are synthetic oils, which means they offer superior fuel economy. However, there are still differences in their fuel consumption, which can also be assessed by their level of viscosity.

Thinner or low viscosity motor/ engine oils require less fuel, which is logical given that they flow easier than thicker oils, and this means the engine requires less energy, or fuel, to move its internal parts. Both 0w-40 and 5w-30 are fuel-efficient because they maintain a good viscosity level that is relatively thinner.

However, 5W30 is thinner (30 compared to 40) at engine running temperature, making it slightly more fuel-efficient than 0w-40. This does not mean that 0w-40 is not fuel-efficient; it is simply not as thin at 100°C as 5w-30.

Range of Temperatures

Until multi-grade oils were introduced, single-grade oils posed problems with changing temperatures because of their limited viscosity. This meant that you might need a different single-grade oil for summers and a different one for winters.

While multi-grade oils are great for a range of temperatures, there are still limits, and you need a different multi-grade motor/ engine oil in Africa than in Atlanta. The temperature ranges for 0w-40 and 5w-30 are slightly different, with 0w-40 offering a wider range.

  • 0w-40 flows normally between -35°C and 40°C
  • 5w-30 flows normally between -25°C and 30°C

This means that 5w-30 is not ideal for Africa, where the temperature may easily run over 30°C, whereas both 0w-40 and 5w-30 will work fine in Atlanta, where temperatures remain within their individual limits.

  • 0w-40 and 5w-30 – When to Use Which Motor/ Engine Oil

The range of temperature, among other things, dictates the motor/ engine oil you use. Since most options today are multi-grade synthetic oils, you can use them for a wide range of temperatures in hot and cold places without worrying too much.

Both 0w-40 and 5w-30 are multi-grade oils that can be used in summers and winters for most parts of the nation. However, if you live somewhere where the temperature exceeds their mentioned individual temperature range, you will want to consider a different option.

It is always best to check your car manufacturer’s recommendation before you opt for any motor/ engine oil.


Overall, the differences between 0w-40 and 5w-30 are not huge. They are both synthetic, multi-grade oils that can function well in the summers and winters while giving you good fuel efficiency. However, if we were to dig deeper, the subtle differences may be important depending on your car and location.

0w-40 is thinner at low temperatures and thicker at engine running temperature than 5w-30, but it has a wider range of temperatures it can function in. On the other hand, 5w-30 is a slightly more fuel-efficient option because of its lower viscosity at engine running temperature.

At the end of the day, you should consider all the mentioned aspects and your car manufacturer’s recommendations before opting for any type of motor/ engine oil. A few other factors to consider include the age of your car, its mileage, and the condition of its engine.