Updated at: 19-07-2022 - By: Lucas

Due to the age of the engine, automobile engines are not meant to run on a single type of oil.

To guarantee that an engine has the best lubricating oil, manufacturers mix and match different oils for different types of engines. Since no two cars are the same, there is no universally effective oil formula.

Oils come in a variety of forms and functions, such as thickness, viscosity, weight, and others, depending on its function and specifications.

Here, we’ll compare 10w40 and 20w50 oil, the two most common grades of oil, to help you decide which is best for your vehicle.

When it comes to protecting your vehicle in the winter and summer, 10W40 and 20W50 have a lot in common. The viscosity index is a key factor in distinguishing the various engine oils. The viscosity index of 10W40 oil is 150, while that of 20W50 oil is 130. Engine oil performance improves with increasing viscosity index.

What Is 10w40 Engine Oil and What Engines Can It Be Used For?

10w40 vs 20w50.

10W40 is one of the most commonly recommended engine oils for today’s engines and cars. The newer engines in all automobiles manufactured after 2012 require additional lubrication and cold temperature pumping.

As a result, 10W40 oil is best suited for high-performance automobiles and cars in cold areas. An engine’s lubrication can be improved by using 10w40 oil, which is recommended for engines that have traveled more than 100,000 kilometers (60,000 miles).

The viscosity of 10W40 is denoted by the name’s digits. Temperatures of 25 degrees Celsius or 13 degrees Fahrenheit are used to measure the oil’s viscosity, whereas 40 degrees Celsius or 104 degrees Fahrenheit is used to measure the oil’s viscosity at operating temperatures.

A higher viscosity oil, such as 10W40, provides greater flow to the engine components and protects the piston skirts and bearings when they are subjected to heat. High-performance engines and contemporary vehicles necessitate the use of a high-quality oil, such as 10W40.

What Is 20W50 Engine Oil and What Engines Can It Be Used For?

Another engine oil recommended by the manufacturer is 20W50. As a result, the oil should only be used in accordance with the instructions provided by the manufacturer.

The 20W50 is the preferred lubricant for vehicles with great thermal efficiency. This oil is particularly well-suited to vehicles used in warm weather, such as those driven during the spring, summer, and early fall. At 16. 3 21. 8 mm2/s, its kinematic viscosity is comparable to that of water.

The engine of your vehicle will heat up if you drive it at high speed for an extended period of time. If the engine components aren’t properly lubricated, this heat might cause catastrophic damage. If you find yourself in this predicament, taking 20w50 can help you deal with the pressure.

A cold start is much more critical when you’re staying in a chilly area where your automobile is left in the garage for more than a few days. Oil in the 20W50 range provides the optimal lubrication for cold-starting an engine.

As a result, 20W50 oil is appropriate for both winter and summer cars because of its low viscosity. Viscosity at low and high temperatures is indicated by the digits in the name of the product.

It is the viscosity of the oil at a minimum of 20 degrees Celsius or 4 degrees Fahrenheit, which is the number 20 and w.

Its viscosity is shown by the number 50, which indicates that the oil can withstand temperatures up to 45 degrees Celsius or 113 degrees Fahrenheit.

Passenger vehicles typically don’t run as long as pick-up trucks or highway fleets. As a result, you’ll have to perform more frequent oil changes.

When it comes to large and elderly vehicle engines, 20W50 oil is the most cost-effective alternative for long-term lubrication and lengthy engine life.

10W40 and 20W50 Oil Differences

10w40 vs 20w50..

1. Viscosity

When it comes to oil viscosity, 10W40 and 20W50 are the same. This means that at low temperatures, 10W40 is more viscous than 20W50, making it the best choice for winter cars.

When it comes to hot conditions, 20W50 is the finest choice. Always remember to adhere to the viscosity grade recommended by the product’s manufacturer.

2. Density

The denser 20W50 weighs in at 872 kg/m3, while the less dense 10W40 weighs in at 865 kg/m3. Using either 10W40 or 20W50 will not result in greater miles per gallon.

3. Additives

They’re both made from high-quality base oils that are combined with additions to fulfill their specific needs. Both oils have excellent heat stability and oxidation resistance as a result.

4. Operating temperature

Compared to 20W50, 10W40 having a lower viscosity at lower temperatures of 25 °C or 14 °F. 10W40 oil has a high temperature viscosity of 40 degrees Celsius (113 degrees Fahrenheit), while 20W50 oil has a high temperature viscosity of 50 degrees Celsius (113 degrees Fahrenheit).

Because of this, 10W40 oil can be used in colder locations, whilst 10W50 oil can be used in hotter ones.

5. Price

If you compare 10W40 and 20W50 oils, you’ll find that the former is more expensive. As a result, if your vehicle is part of a highway fleet that requires frequent oil changes, 20W50 is a more cost-effective option than 10W40. Light vans and passenger cars that don’t require frequent oil changes do well with 10w40.

Can I use 10W40 instead of 20w50?

We’ve established that the sort of oil you should use is dependent on the season, the vehicle you’re driving and the speed at which you’re driving, among other factors. Oil can damage an engine if used in excess in a vehicle that requires 20W50.

Regardless of the vehicle you drive, some mechanics may advise you to use 20W50 or 10W40 in your monthly maintenance regimen.

If you want to know what oil is best for your car’s engine, consult your owner’s manual and your mechanic, both of whom have a lot more knowledge about cars and engine problems than you have.

Is 10W40 the same as 20w50?

No, the two types of engine oil are very distinct. However, 10w40 is the most common oil to work with. In rare cases, 20w50 can be used.

What happens if I put the wrong oil in the engine?

Engine damage is possible if the improper type of oil is used in the engine. The vehicle’s strength will deteriorate, and it will no longer lubricate properly. Varying oils have different viscosities and flow properties.

As a result, oil leaks and engine noise are common when the improper oil is used. Additionally, putting the wrong engine oil with a lower winter or cold viscosity than what the manufacturer recommends can cause the car not to start in cold weather.

Sludging should not be a problem if you perform regular oil changes with either 10W40 or 20W50.


Each oil is distinctive in its own way, and it’s impossible to generalize about them all. Because of this, it is critical that you use the correct type of engine oil to keep your car running smoothly and prevent engine issues.

To find out what kind of oil is best for your vehicle, see the owner’s manual provided by the manufacturer. To choose the best oil from a compatible 10W40 and 20W50, look at the differences and similarities between the two oils.