10W50 vs 10W40: A Comprehensive Guide

Naomi O'Colman

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10W50 vs 10W40

10W50 vs 10W40

To reduce friction and wear and tear caused by the moving parts of the car, motor oil is used to lubricate the engine components. Of course, in order to protect a powerful engine, the oil grade needs to be greater.
There are several sorts of oil based on varying grade and viscosity. Today, I’ll outline the differences between 10w50 vs 10w40 in this article.

What is 10W50 Engine Oil?

10w50 Engine Oil is a type of oil that is used to lubricate and protect internal combustion engines. It is a multi-grade oil, meaning that it has properties that range from 10 to 50 viscosity depending on the temperature at which it is operating.

10w50 is a thicker oil than other standard motor oils, making it ideal for high-performance engines in extreme climates.

So what makes 10w50 oil superior to others? It provides excellent protection against wear and corrosion, keeping your engine running smoothly even under heavy workloads. This oil also helps to reduce friction between moving parts, allowing them to operate more efficiently and last longer. Its thermal stability ensures that it resists break down even when subject to intense heat.

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10w50 engine oil helps keep fuel consumption low while providing optimum performance in any environment.

Pros of 10w50:

  • Suitable for high-performance engines
  • Protects against wear and corrosion
  • Reduces friction between moving parts
  • Resists breakdown in extreme heat
  • Low fuel consumption

What is 10W40 Engine Oil?

10W40 engine oil is a type of motor oil designed to help reduce friction and keep the engine running smoothly. It comprises a blend of synthetic and mineral oils with a viscosity index between 10 (thinner) and 40 (thicker).

10W40 oil is a popular multi-grade oil that is commonly used in a wide range of vehicles. It has a viscosity rating of 10 in cold temperatures and 40 in hot temperatures, making it a versatile oil that can be used in both warm and cold climates.

10W40 oil helps keep the engine clean by helping prevent sludge build-up. It also helps to protect against wear on internal components, including bearing surfaces, piston rings, and valvetrain components.

Additionally, it is formulated to meet the needs of both gasoline and diesel engines. The viscosity index of 10W40 provides excellent protection at start-up, while still providing superior protection even at high temperatures. This makes 10W40 oil an ideal choice for modern engines that tend to run hotter than older models.

Pros of 10w40:

  • Keeps your engine running smoothly
  • Reduces friction
  • Prevents sludge build-up
  • Protects internal components from wear
  • Meets the needs of gasoline and diesel engines

What Distinguishes 10W40 Engine Oil From 10W50 Engine Oil?

Because oil is a lubricant, it helps moving parts move more readily by reducing friction between them. By doing this, you can stop the engine from deteriorating and from overheating or cooling.
Because it provides a good blend of low-temperature flow, high-temperature protection, shear stability, and chemical stability for long-life performance under challenging conditions, a typical modern engine will use a 10w-40 or a 10w-50 oil.

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When oil is cold, the greater the “W” number, the thinner the oil is. The thickness at low temperatures increases with decreasing number. Engine oil typically has an SAE grade of 5W-20 or 5W-30.

According to your engine. As long as the engine is still functioning within the normal operating temperature range, using a lesser weight (thinner) of oil will not cause any harm if you use a greater oil weight since your engine was built for it.

Using 10W50 oil for:

High-performance engines and sports automobiles that need more lubrication and protection often use 10W50 oil. This type of oil is suited for engines that run at higher temperatures and pressures since it has a thicker viscosity than lower-weight oils.

High-performance cars like the BMW M3, Porsche 911, and Ford Mustang Shelby GT500 are a few examples of automobiles that may need 10W50 oil. For some racing engines and motorbikes, it might also be advised.

The manufacturer’s recommendations for the right oil weight and type to use in your vehicle are crucial, therefore it’s important to keep in mind that not all vehicles require 10W50 oil. It is always preferable to seek guidance from the owner’s manual or a skilled mechanic because using the incorrect oil weight can harm engines and violate warranties.

How about 10w50 in old engines? There is no danger in using it if you have a vintage car (or any engine that uses 5W-30 or 10W-30 oil) that needs a 10W-50 grade.

The heavy viscosity of 10W-50 won’t harm anything since these engines are made to run with thinner oil. The thicker oil won’t offer any additional protection until the engine requires higher temperatures than usual; thus, there is also no benefit.

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Using 10W40 oil for:

A popular multi-grade oil that is frequently used in a variety of vehicles is 10W40 oil.  Engines with lesser horsepower requirements and need the oil that flows effectively at lower temperatures often utilize 10w-40. These engines, which normally produce 175 horsepower or fewer, are present in most cars today.

Vehicles with gasoline engines, such as passenger cars, light-duty trucks, and SUVs, can use this oil. It is also frequently used in older or high-mileage engines, which might benefit from using an oil that is a little bit thicker to help minimize oil leaks and lessen engine wear.

10W50 vs 10W40

Let’s concentrate on the distinctions between the two. On the basis of fuel efficiency, viscosity, and hot weather, we shall distinguish between them.

Fuel efficiency

The 10w40 motor oil is designed for engines with low horsepower requirements, and it is typically used in vehicles with lower output. However, since the introduction of 0w20 and 5w20 motor oils, fuel economy motor lubricants have gained popularity.

Many of these motor oils will boost fuel economy by at least one to two percent. You only need to know that lighter oils will provide you with greater gas mileage because of their low viscosity, making them easier to transfer through the oil system.


The viscosity of 10w40 and 10w50 oils is the same at absolute zero. They are recognized as belonging to the same class. The 10w50 motor oil will have a higher viscosity than the 10w40 motor oil when operating at 100 degrees Celsius.

The viscosity index for both the 10w40 and 10w50 motor oils is one hundred sixty and one hundred sixty-seven for the latter. As a result, the viscosity of 10w50 motor oil will vary more subtly over the temperature range. As a result, both oils will function similarly at low temperatures.

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However, at operating temperatures, 10w50 motor oil will provide higher protection than 10w40 motor oil. Additionally, due to its high viscosity, the 10w50 motor oil will require more effort to pump than the 10w40 motor oil.

High temperature

10W50 vs 10W40 A Comprehensive Guide

The engine oil will be thinner when cold if the W number on it is higher. And the thicker it will be in cold temperatures, the lower the number.

The ability of the motor oils to become thin in hot temperatures is what distinguishes 10w40 motor oil from 10w50 motor oil. While the temperature of the 10w40 motor oil rises, the 20w50 motor oil will not thin as quickly, but it may become overly thick when operating in low temperatures.

Can I Substitute 10W50 for 10W40?

Yes, you can, but you must still follow the advice provided in your owner’s manual. For instance, a modern car’s engine, which needs a 10w40 oil, won’t benefit from the extra protection provided by a 10w50 motor oil.

In that case, you must consistently follow the manufacturer’s advice for your car. Using an oil that is not advised by your vehicle’s manufacturer can hasten the onset of problems.

10W40 Vs 10W50 Which is Better?

The best oil to use relies on several variables, including the type of vehicle, the state of the engine, and the climate. When selecting between the two oils, keep the following in mind:

  • When it comes to viscosity, 10W40 and 10W50 oils are similar when they’re hot, but 10W50 is thicker when it’s colder. If you live in a warmer area, 10W40 might be adequate, however, 10W50 might offer superior cold-start protection if you reside in a colder climate.
  • Engine condition: 10W40 might be a better option if your engine has high mileage or is prone to leaks because it is a little thinner and might run through the engine more freely. But, 10W50 might provide superior protection and lubrication if your engine is high-performance or runs at high temperatures.
  • Manufacturer advice: For the right oil weight and kind to use, always follow the advice of the vehicle’s manufacturer. The improper oil can cancel warranties or harm engines.
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Generally, both 10W40 and 10W50 oils are appropriate for a wide range of cars; the decision comes down to personal requirements and environmental factors. For guidance on the proper oil weight and type to use in your particular vehicle, it is always advisable to check the owner’s manual or a trained mechanic.


#1 What is the difference between 10W40 and 10W50?

The difference between 10W50 and 10W40 motor oil is the viscosity. 10W50 has higher viscosity than 10W40, meaning it’s thicker and will cling to the surface of the engine better at high temperatures. This higher viscosity makes 10W50 better suited for engines that may be under greater stress or strain due to frequent high-performance driving, such as racing or off-roading.

Conversely, 10W40 has lower viscosity than its thicker counterpart, making it thinner and more able to flow through smaller passages in an engine. This makes it better suited for daily drivers who may not be putting their vehicle under the same kind of stress as racers and off-roaders do.

#2 What is 10W50 temperature range?

The temperature range for 10W50 motor oil is typically from -30 °C to 100 °C, although the exact range may vary depending on the manufacturer and specific product. This viscosity grade of oil is often used in high-performance engines that operate under extreme conditions, such as racing or off-roading, where engines are subject to frequent thermal shock.

#3 What are the disadvantages of 10W50 oil?

The major disadvantage of 10W50 oil is that it can be too thick to properly lubricate some engines, particularly those in older vehicles.
Moreover, the increased viscosity of the oil may require more frequent oil changes because the thicker oil may not flow as freely throughout the engine as a more lightweight oil.
In addition, many modern engines that use 10W50 oil may experience reduced fuel economy due to its increased thickness.
Finally, when using 10W50 motor oil in cold climates, it can thicken even further, which can cause issues with hard starting and possibly even engine damage due to inadequate lubrication.

#4 What oil may I use in place of 10W40?

You could use 10w30 oil instead of 10w40. 10w30 is a multi-viscosity grade that can provide improved fuel economy and better protection against wear and tear. It is designed to improve cold-weather starting and has a narrow temperature range of viscosity.


The viscosity index of oil indicates how thick or thin it is at various temperatures. When it gets cold, an oil with a higher viscosity index will be thinner than one with a lower viscosity index and won’t flow as well. You should frequently check it for your particular engine.

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