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15W50 VS. 20W50: What Is The Difference Between These Two Motor Oils?

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Hi, I'm Azim Uddin, a student who loves cars. Visit to learn about car maintenance for beginners and experts. In my studies, I found a cool connection between hosting and car care. Join me on this journey where every road has a story, and hospitality meets the thrill of cars. Explore, learn, and enjoy the ride with me!

Last Updated on May 10, 2024 by Azim Uddin

Choosing the right motor oil can be difficult. Anyone can be confused by the vast array of options with cryptic numbers and letters on their labels. Among the numerous options, 15W50 and 20W50 are two popular viscosities that cater to various engine needs.

So, what is the difference of 15W50 vs. 20W50? The main distinction between 15W50 and 20W50 motor oils is their viscosity at low temperatures. In cold weather, 15W50 is thinner and flows better, while 20W50 is slightly thicker. Furthermore, 15W50 is suitable for various conditions, whereas 20W50 is often preferred for hot climates.

Read on to decode what these numbers mean and explore the differences between 15W50 and 20W50. This information will also help you decide which one is the best fit for your vehicle.

Comparison Table: 15W50 vs. 20W50

Let’s kick things off with a quick side-by-side comparison of 15W50 and 20W50 engine oils:

Comparing Aspects15W5020W50
Viscosity at Low Temperatures (15W or 20W)Better cold-start performance, suitable for colder climates.It may not flow as well in extremely cold weather like 15w50.
Recommended Usage:Versatile, suitable for both hot and cold climates.It is ideal for warmer climates and older engines.
Fuel EfficiencyOffers slightly better fuel efficiency.Has a negative impact on fuel economy.
Common ApplicationsModern engines, year-round use.Older cars, hot climates, and heavy-duty applications.
Price Range$15 and $17$25-$35
Comparison Table
15w50 vs 20w50

Meaning Of 15w50 And 20w50

These numbers provide vital information about the oil’s behavior at low and high temperatures. This will help you make an informed choice for your vehicle’s needs.

See also  0w40 vs 5w30: A Complete Breakdown of Oil Grades

The First Number (15 or 20)

15 and 20 represent the viscosity of the oil at low temperatures. The letter “W” indicates that the oil has been tested for performance in colder temperatures.

In cold weather, the lower the first number, the better the oil flow. As a result, 15W50 oil flows more easily in cold weather than 20W50 oil. In practice, this means that 15W oil is an excellent choice for colder climates or for vehicles parked outside during the winter.

The Second Number (50)

The second number, in this case, 50, indicates the oil’s viscosity at high temperatures. This is measured at 100°C as it is the working temperature of a standard engine.

A higher number in this category indicates that the oil thickens at high temperatures. This provides better protection for your engine under extreme conditions.

Both 15W50 and 20W50 have the same second number, indicating that they have similar high-temperature viscosity characteristics. These numbers are based on the SAE (Society of Automotive Engineers) classification.

Differences Between 15w50 And 20w50

Here are the main differences between 15w50 and 20w50.

Viscosity at Low Temperatures

With a lower first number, 15W50 oil flows more easily in cold weather, ensuring better lubrication during cold starts. This makes it an excellent choice for colder climates.

At low temperatures, 20W50 oil becomes slightly thicker, resulting in a slower flow during cold starts. While it is not the best choice for extremely cold weather, it provides adequate protection in milder winters.

Recommended Usage:

15W50 is a versatile oil that can be used in a variety of climates and with a variety of engine types. It’s an excellent choice for a year-round motor oil that withstands extreme cold and heat.

See also  10W30 Vs. 5W30: Head-to-Head Comparison to Choose the Better Oil

20W50 is more specialized and is best suited for warmer climates and older engines. It’s also a popular choice for vehicles used for towing, off-roading, or other demanding activities.

Fuel Efficiency

Because of its lower viscosity at low temperatures, 15W50 provides slightly better fuel efficiency. This is because the engine uses little energy to circulate the motor oil during cold starts due to its flowability.

While 20W50 is less fuel-efficient during cold starts, the impact on overall fuel economy is negligible. If you prioritize other factors, such as engine protection, this should not be a major concern.

Engine Protection

The 15W50 provides excellent engine protection in various conditions. This makes it an excellent choice if you own a vehicle with a modern engine. It is also suitable for a vehicle that requires consistent performance all year round. It excels at protecting engines from wear and tear.

Because of its thicker viscosity, 20W50 provides strong engine protection, especially in hot climates and under heavy loads. As a result, it is a preferred option for older vehicles, particularly those with flat tappet camshafts.

This is because they require additional protection. 20w50 is also suitable for high-performance engines or those subjected to demanding tasks.

Price Range

The price of 15W50 and 20W50 oils can vary greatly depending on brand and quality. In general, 20W50 is more expensive, with prices ranging from $25 to $35 per liter.

15W50, on the other hand, costs between $15 and $17 per liter. This makes it an appealing option for those on a tight budget. Now that you understand the differences between 15W50 and 20W50, the question remains: which one is best for you?

Which Is Right For You: 15w50 Vs. 20w50?

Here are some guidelines to help you make the right decision:

  • If you drive a modern vehicle, the 15W50 is a solid choice. Its versatility ensures your engine is protected in all conditions.
  • For high-performance cars, 20W50 is often the preferred option due to its ability to protect engines under extremely hot conditions due to its viscosity.
  • If you live in a region with cold winters, 15W50’s lower first number ensures better flow in cold weather. This makes it a smart choice for areas with freezing temperatures.
  • If you own an older vehicle, 20W50 provides the extra protection that older engines need. It helps to prevent wear and tear in engines that have seen their fair share of miles.
  • For hot climates, 20W50 is well-suited to hot weather. Its thicker viscosity ensures your engine stays well-lubricated even in scorching conditions.
  • Heavy-duty use: If your vehicle is involved in towing, off-roading, or any heavy-duty tasks, 20W50 is a reliable choice.
  • Budget considerations: 15W50 is often the more economical choice.
See also  20w40 vs 10w40: Which Viscosity is The Best for Your Engine in Winter?

Confused about choosing the right oil between 20W40 and 20W50? Our article on 20W40 vs. 20W50 breaks down the differences. Check out our resource for more information.


Let’s address some commonly asked questions further to clarify the differences between 15W50 and 20W50 motor oils.

Q1. Can I mix 15W50 and 20W50 motor oils?

Yes, you can mix the two oils; it will not harm anything. However, it’s best to stick with one type of oil that suits your engine’s needs.

Q2. How often should I change my motor oil?

The frequency of oil changes is determined by your vehicle, driving habits, and the type of oil you use. Oil should be changed every 3,000 to 5,000 miles as a general rule, but check your vehicle’s manual for manufacturer-specific recommendations.

Q3. What happens if I use 15W50 oil in a hot climate?

Using 15W50 oil in a hot climate isn’t always a problem. It provides adequate protection in high-temperature conditions, too. In extremely hot climates, however, the 20W50 may provide slightly better engine protection.


The choice between 15W50 vs. 20W50 engine oils is entirely dependent on your vehicle and driving conditions. The numerical codes on these oil labels represent their viscosity at low and high temperatures.

Because of its versatility, 15W50 is a popular choice for those looking for year-round dependability, especially in climate-variable areas. It excels at protecting engines from the rigors of extreme cold and high heat.

The thicker viscosity of 20W50, on the other hand, lends itself to situations where engine protection under extreme heat and stress is critical. This makes it a popular choice for older vehicles and hot climates.

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