Difference Between 5w20 and 5w30

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Undoubtedly, it’s crucial to choose the proper kind of motor oil for your vehicle in order to ensure its smooth running. Neglecting your motor, you will definitely fail to feel all the benefits of your car.

Clearly, many automobile owners turn to professional mechanics to change the oil. However, even if you don’t change the oil yourself, it doesn’t mean that you can be unaware of what’s going on inside your vehicle. Remember that you need to understand what oil is the most appropriate for your engine. This information can be of great use for you if you have no possibility to turn to a professional.

In order to maintain a motor in good condition, every car owner needs to change the oil in time. Here, we offer you a comparison of 5w20 and 5w30 motor oils as both of them work great in hot as well as cold temperatures.

What Is Viscosity?

The Society of Automotive Engineers differentiates motor oils by their viscosity features from low to high: 0, 5, 10, 15, 20, 25, 30, 40, 50 and 60. In short, viscosity means liquid’s resistance to travel.motor oil viscosity explained

Too watery liquids have low viscosity ratings while thick fluids (like honey) have high viscosity levels. Letter W usually stands behind numbers 0, 5, 10, 15 and 25, signifying “winter” or low temperatures, not weight. Remember that the viscosity index of the motor oil may change depending on temperature and weather conditions.

Nevertheless, talking about kinematic viscosity, the index is based on oil’s aptitude to travel through a conventional port at standard temperatures. The longer it streams, the higher the SAE rating it gets. Thus, it’s evident that 5w30’s viscosity exceeds the one of 5w20.

Difference Between 5w20 and 5w30

As we have already mentioned, W signifies “winter”.

The number before this letter signifies the oil weight in cold or non-heated ambience. Cold climate or frosty season may affect the oil weight and the way it runs through the motor.

5w20’s Winter rating equals 5 and will operate as a 20 weight oil with heat. Long ago, when this rating of engine oils was first created, cars were driven much easier in winter than today. The thing is that they had no 4-wheel drive abilities, peculiar to contemporary SUVs and other automobiles. Consequently, winter viscosity wasn’t a problem for drivers.

Nowadays drivers must take care that they are applying only the advisable type of motor oil. In order to see the importance of choosing the right oil, you should be aware of the fundamental formulas for motor oil. The higher the rating, the thicker the oil is. Thus, 5w30 will flow less smoothly than 5w20. When the motor is cool, its viscosity is almost identical. However, when it operates, it heats and the difference is pretty observable.

Consequently, 5w30’s winter index is the same, but it operates as a 30 weight oil in the heated ambience.

You should know that many cars accept oils with a couple of possible viscosity levels. Thus, you will not face any serious troubles with your engine by applying 5w30 instead of 5w20.

However, it’s crucial to know what exactly your vehicle needs and provide it with the best possible option.

Let’s see the main differences between 5W-30 and 5W-20 of Castrol GTX:

Characteristics Castrol GTX 5W-30 High Mileage Engine Oil Castrol GTX 5W-20 High Mileage Engine Oil
SAE Grade 5W-30 5W-20
API Service SN Plus SN Plus
Flammable No No
Motor Oil Type Conventional Conventional
Maximum Operating Temperature (°C) 180 180
Maximum Operating Temperature (°F) 356 356
Minimum Operating Temperature (°C) -35 -35
Minimum Operating Temperature (°F) -31 -31
Pour Point (°C) -39 -48
Pour Point (°F) -38 -54
Flash Point (°C) 200 200
Flash Point (°F) 392 392

5w20 vs 5w30: Which Oil Ensures Better Gas Mileage?

Oils with lower viscosity like 5w20 build a thinner block of protection at normal temperatures. As the lesser amount of oil is in between the moving details of your motor, it will provide better performance due to low friction. Thus, the application of low viscosity engine oil leads to enhanced fuel efficiency.

Though the raise in your MPG maybe not evident, still, it will have some enhancements. Some automotive forums and blogs claim that better fuel efficiency demands extra investments. Actually, many experts assure that usage of 5w20 instead of 5w30 will inevitably ruin your motor and lead to its shorter lifespan.

So, 5w20 and other low viscosity oils will give less protection to the motor than the ones with higher ratings in regular conditions.

Simultaneously, it’s more reasonable to apply them in regions with cold climates and frosty weather as they will guarantee more efficient motor functioning under low temperatures.

What Is Better: 5w20 or 5w30?

Seeking the best oil for your car, several factors must be considered. Though both these oils have approximately the same level of protection provided, they still differ in their viscosity index. If you dwell in a hot region, 5w30 is most appropriate as it functions better at high temperatures and protects your motor more efficiently.

However, 5w20 is a better option for a cold climate as it’s more fluid and heats up faster. If you live in a region with a mild climate, both oils are appropriate.

To Sum It Up


Synthetic motor oils are versatile. Thus, both 5w20 and 5w30 will function properly to ensure the necessary level of protection for your engine no matter what climate you live in. However, if you are still contemplating on what option is the best for your automobile, give preference to 5w30.

Comparing to 5w20, 5w30 keeps a greater level of film and shear strength. Moreover, it operates smoothly regardless of automobile type, ambiance, and temperature. Though, it’s important to keep in mind that the difference is rather mild and so, you are free to opt for 5w20 if you fail to find 5w30.

Best 5W-30 Motor Oil

Best 5W-20 Motor Oil:

Last update on 2021-07-07 / Affiliate links / Images from Amazon Product Advertising API

Dan Hoffman

Dan is a co-founder of Engineswork. He knows everything about internal combustion engines. Ask your questions in comments down below this article - he will be glad to help you anytime.

2 thoughts on “Difference Between 5w20 and 5w30

  1. Steve Saca says:

    Hey Dan. I have a Question. I have a Jeep Commander 2007 3.7v6. Now its mileage goes 140,000. The oil cap and manual says and recommend to use a 5w20. Can I change to a 5w30? I live in NC, Franklin.

    1. Dan Hoffman says:

      Hi, Steve.
      Your Manufacturer says: Lubricants which do not have both, the engine oil certification mark and the correct SAE viscosity grade number should not be used.
      So, as You said 5W20 is perfect.
      As for me, I can tell you that using a 5W-30 for your vehicle after 140,000 would be even better and I’m pretty sure it won’t cause any problems.

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