engine oil

There are several grades of engine oil you can find in the market. It’ll sometimes be a frustrating and confusing ordeal to figure out which grade oil to use in your car/vehicle.

Here’s an important thing to note. The correct grade oil you can use for your car can be found in the owner’s handbook.

engine oil

Some of the commonly recommended car oil grades are 5W30 and 5W40. These engine oils are the ideal ones to use in most weather conditions.

But what does the grading actually mean? And how do the 5W30 and 5W40 grade engine oils differ from each other?

If you have these questions, then keep reading!

In this post, we’ll be having a closer look at what does the 5W30 and 5W40 engine oil mean, what are the differences between the 5W30 and 5W40 engine oils and much more.

So without wasting any time, let’s jump into it!

What does a 5W30 Car Engine Oil Mean?

If you own a car and you look for the oil marking, you’ll come across SAE 5W30. Ever wondered what it is? Well, here’s the answer for that.

SAE actually stands for society of automotive engineers while the 5 and 30 markings denote the oil viscosity. The greater the number is, the higher the viscosity of the oil will be.

The W stands for winter. What all these markings simply mean is that even on a minus 25 degree temperature, the oil will function normally and get your car started.

The main goal of the engine oil is to protect the engine from very low winter temperature. To do that, the oil must be lighter and it must be able to run the car engine without any difficulties. It should be able to start the engine during the cold climate and it should be dense enough to keep the engine running in the same temperature. The oil must increase the viscosity when the temperature is high and it has to decrease it if the temperature is low. When the above conditions are met in a particular engine oil product, you’ll be able to use it throughout the year.

If engine oil functions properly only in a particular season like either summer or winter, then it is called the mono oil. Similarly, an engine oil that meets all weather conditions, they are called multi-grade oils. In order to obtain a multi-grade engine oil, conventional additives needs to be added to the various motor-oil base additives such as the SAE base.

This decreases viscosity during cold starts, and at the same time, it increases the viscosity of the engine running temperature. Engine oils belong to the universal lubricant oils category.

To understand the 5W30 engine oil’s real capacity, conduct your own oil test. This’ll show the original nature of the oil and at which point the product eventually loses its characteristics.

What does a 5W40 Car Engine Oil Mean?

The same description for the SAE 5W30 oil fits perfectly to the 5W40 engine oil. In order to figure out a more economical ride for the car owners, the US engineers have introduced several parameters to provide a certain combination of 5W40 viscosity oils. These parameters specifically targeted towards reducing the oil consumption considerably.

The major characteristics of 5W40 car engine oils include starts the vehicles easily even at low temperature, maintains high-oxidation stability, increases the interval for the engine oil replacement, keeps the stability of the oil film for a long time and contains good detergent properties.

Differences of the 5W30 vs 5W40 Engine Oil

There are various differences between the 5W30 and 5W40 engine oils.

  • You can find several differences in the working viscosity of both the engine oils. While the 5W40 engine oil has a 12.5 to 16.3 MM2/s at 100g working viscosity, the 5W30 oil has a 9.3 to 12.5 MM2/s at 100g viscosity. Both oils are 5 grade when the engine is cold, but the 5W30 is 30 grade and the 5W40 is 40 grade during its operation.
  • Both the engine oils sustain in extreme loads, but the 5W40 is slightly better than the 5W30.
  • The temperature range for 5W30 and 5W40 engine oils vary significantly. The 5W30 oil is used in the temperature ranges from minus 25 degrees to 25 degrees. But the 5W40 engine oil is used in the temperature ranges of minus 25 degrees to 35 degrees.
  • Considerable oil flow difference. The 5W40 provides higher pressure but less oil flow. But on the other hand, the 5W30 provides significantly higher oil flow. The pressure will be a lot low in this engine oil category.
  • The fuel economy differs for 5W30 and 5W40. The 5W30 has a greater fuel economy than the 5W40 engine oil category.
  • The application of 5W30 and 5W40 engine oil has major differences in terms of vehicle usage and temperature. The 5W30 engine oil can be used in almost all vehicles and they are generally used for colder temperatures. Whereas, the 5W40 engine oil performs really well in warmer temperature and it is used in high mileage engines.
  • The 5W30 engine oil is typically pricier than the 5W40 variant.


We hope that this guide on the differences between the 5W30 and 5W40 engine oil would have provided you answers for all your questions. Read the car owner’s handbook carefully, determine which engine oil you need for your vehicle before you go to purchase a particular variant.

Want to include your thoughts about this guide? Put them in the comments section below!

FAQs about the 5W30 and 5W40 Engine Oil

What Happens if You Use 5W40 Instead of 5W30 Engine Oil in a Vehicle?

When you use a different engine oil instead of the recommended one, your engine may experience wear and damage. The SAE 5W40 may be thin at all temperatures, but the SAE 5W30 will be extremely thinner in the high heat temperature.

Which is thicker 5W30 or 5W40 Engine Oil?

The 5W30 engine oil is just that bit more thicker than the 5W40 variant. Both have their separate temperature requirements in which they perform really well.

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Lara Herrington
With over 12 years of experience, she is a proficient content writer and editor specializing in a diverse range of subjects, including technology news, country news, arts, science, travel, and automobiles.


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