Can you put 10w30 in a 5w20 engine? Only Facts!

The primary purpose of the engine oil is to improve the lubrication between the different metal components in order to reduce the friction. 10w30 and 5w20 are two of the most commonly used grades of engine oils that represent two different ranges of viscosity.

However, the question of the hour is whether you can put 10w30 engine oil instead of 5w20? Well, it is as simple as pouring the 10w30 bottle down in place of a 5w20, but would the car run well? It would exactly run as you would, if you put on a shoe that is larger by a couple of sizes.

Basically, the car would still run but it is likely that you would experience problems like reduced mileage and a severe drop in the performance of the vehicle. So, it is not recommended to use 10w30 engine oil in engines made for 5w20 engine oil.

So, let’s start with a table comparing both the engine oils in different parameters–

Suitable EnginesHeavy Duty Engines (Transport Trucks & Commercial Buses)Light Engines (Small Petrol & Diesel Vehicles)
Fuel EfficiencyLowHigh
Exposure to high TemperaturesVery Durable, Doesn’t Evaporate EasilyEvaporates Easily
Engine PerformancesLow Performance, High PowerHigh Performance, Low Performance
Suitable ClimateWarm ClimatesCold Climates

Similarities and Differences Between 10w30 vs 5w20 Motor Oil

Since both the oils are specifically designed to fulfil their purposes in two different types of engines, they have very a few relevant similarities that are worth referring to. However, both the engine oils have several important differences that need to be discussed.

Differences between 10w30 and 5w20 engine oils are –

Suitable Engines

The 10w30 is a multi-grade engine oil suited for heavy duty engines such as in commercial trucks and buses that performs well at high temperatures due to its thick nature and high viscosity while 5w20 engine oil is a multi-grade engine oil that is thinner than the 10w30 oil, due to which it functions better in smaller petrol or diesel engines. While 10w30 lubricates better at higher temperatures, 5w20 gets evaporated at high temperatures and leads to reduced lubrication.


Owing to the higher viscosity, 10w30 engine oil is thicker at normal temperatures than 5w20, which has lower viscosity. The thickness of the 10w30 oil helps it protect the engine parts while the thinner 5w20 oil is beneficial in helping improve fuel economy and facilitating easier ignition during the colder winters.

Pro Tip – While it is recommended to follow the viscosity as mandated by the user manual of the car, the quality and specifications of engine oils with same viscosity differ for each brand. So, it is best to do your research and compare the bench tests to select the right brand for your car.

Fuel Efficiency

Due to its higher viscosity, 10w30 oil has reduced lubrication and it requires more effort to pump the fuel, leading to increased fuel consumption. However, the 5w20 oil has lower viscosity and hence improves lubrication leading to easier pumping of the fuel and increased fuel efficiency. Thus, 5w20 oil is much more fuel efficient than the 10w30 oil.


Also Read:-

Can you put 5w30 in a 5w20 engine?

Exposure to High Temperatures

Due to the thickness of the fuel, 10w30 is much more durable at high temperatures, which makes it ideal for heavy duty engines which operate at higher temperatures. However, since the 5w20 oil is thinner, it is not as durable and tends to evaporate easily at higher temperatures.

Engine Performance

The 10w30 engine oil is suited for heavy duty engines which operate at high temperatures. So, 10w30 engine oils are used for a more power oriented performance. Meanwhile, the 5w20 engine oil is suited for smaller engines, which means it prioritizes better performance and fuel efficiency instead of high power.

Suitable Climate

As the name denotes, 5w20 engine oil has a lower viscosity than 10w30, which means it flows more freely even at lower temperatures and provides the benefit of starting more easily. However, due to the higher viscosity, 10w30 becomes very thick and is unlikely to ignite the engine very easily. So, it is best suited for warmer climates where the temperature doesn’t fall too low.

Also Read:-

5w30 vs 5w40 Engine Oil | Complete Difference with Facts


What are the disadvantages of using 10w30 oil in a 5w20 engine?

Each engine has been specifically designed for a specific grade of engine oil. So, it is always best to refer to the user manual that comes with the car. However, if you do use 10w30 in a 5w20 engine, it may lead to several negative effects on your car –

  • Ignition – Since 10w20 oil is thicker and combusts at a higher temperature of -18° to 30° Celsius, it may make ignition harder, especially in lower temperatures. Since the thinner 5w20 oil lower combustion range of -30° to 35° Celsius, it allows for easier ignition. So, if you use 10w30 instead of 5w20, it is likely that you may end up trying to start your engine for hours on a cold winter morning.
  • Engine Stress – Since the engines suited for 5w20 are generally light duty, it is likely that they exert less pressure on components such as bearings and the rod holding up the rotating shaft. Using the thicker 10w30 oil is more likely to increase the pressure on such components due to its thickness and reduced lubrication. Similarly, parts such as the nozzles which are better suited to thinner oil such as 5w20 are likely to choke up due to the restricted oil flow of the 10w30. So, it is likely that using 10w30 oil in a 5w20 engine may lead to exertion of undue pressure and increase the wear and tear of your engine.
  • Fuel Efficiency – Due to its thickness, the 10w30 oil will take more efforts to pump the fuel, unlike the 5w20 oil which is thinner. So, eventually it will affect the fuel efficiency by increasing the number of ignition attempts it takes to get your 5w20 engine started. It also has less lubrication as compared to 5w20 oil, which means that the engine will have an increased drag from the hike in friction between the components, affecting the fuel economy negatively.

What happens when you put 10w30 oil in a 5w20 engine?

A 5w20 engine is made for engine oils with lower viscosity. An oil of lower viscosity is thinner and usually flows easily. However, if you choose to put 10w30 oil, which is not meant for the 5w20 engine, there are bound to be some effects. 10w30 oil is thicker and is made for heavy duty uses but an engine built for 5w20 oil specification is usually suited for lighter purposes. So, if you use heavy duty engine oil in an engine meant for thinner engine oil, the oil flow is bound to be impeded. Similarly, there will be an increased pressure on the engine components due to the higher viscosity and may affect the engine in the long run. Further, there may be complications regarding the ignition since 5w20 oil tends to ignite easily unlike the 10w30 oil, which means more attempts are required to start the engine, especially during the winter season or in extremely cold climates. Thus, putting 10w30 oil in a 5w20 engine is likely to cause serious problems for your engine.

Will it hurt to use 10w30 oil in a 5w20 engine?

Yes, it will definitely hurt the 5w30 engine if you use 10w30 oil. It is like trying to fit into a shoe that was never made to your size. So, consequences are inevitable. In case of 5w20 engines, it could severely decrease the life of your engine as well as lead to problems such as increased fuel consumption and increased attempts at starting your engine in cold temperatures. A 5w20 engine is specifically designed for lighter engine oils and replacing the same with heavier oil such as 10w30 could put severe stress on the engine components and lead to severe wear and tear. So, it is best to go by the directions as referred to in the user manual and not try to use 10w30 oil in a 5w20 engine as it could cost you heavily!

Can you use a mix of 10w30 and 5w20 oils in a 5w20 engine?

No, while you can definitely give it a shot, but the fact is that both the oils are of different grades. So, if you try to mix the same, it would simply form two separate layers. So, it could be of no practical help to mix the two grades of engine oil together since it does not offer any improvement in performance. However, the mixing of oil could lead to an imbalance in the overall viscosity and impeded the proper circulation of the oil to the different parts of the engine, leading to increased wear and tear. Further, due to the inability of the two oils to mix and the presence of varied fuel additives, it could lead to unpredictable performances of your car.

Will using 10w30 oil in a 5w20 engine affect its performance?

Yes, using 10w30 oil in a 5w20 engine will indeed affect its performance. As per the Society of Automotive Engineers (SAE) grading, these two oils have different viscosity and they are suited for engines which are very different from each other. While 10w30 oil is suited for heavy duty engines, 5w20 oils are likely to go best in a lighter engine. So, while it may not affect the direct performance of the engine in the day to day, the primary affects can be seen when the temperature drops drastically. In lower temperatures, the 10w30 oil is likely to thicken unlike the 5w20. So, once the oil thickens, the lubrication reduces drastically and the oil flow gets impeded. It could hamper the performance of the vehicle and also lead to long term implications for your vehicle.


In conclusion, it is important to highlight that while you can definitely put 10w30 in a 5w20 engine in normal climatic conditions, the difference arises when the temperature drops. In comparing the two grades of engine oil, you can see that the viscosity of 5w20 is much lower than 10w30 oil and each has its own set of characteristics.

The 5w20 engine is specifically designed to operate with the 5w20 engine oil. If there didn’t exist any differences, there would have been no real purpose to create two different grades of oil, namely 10w30 and 5w20. The 5w20 engine is designed to work with thinner engine oils such as 5w20 oil to help improve fuel economy.

To use thicker oils such as 10w30 would lead to increased fuel consumption and simply defeat the purpose of trying to make the 5w20 engine oil fuel efficient. Further, the 10w30 oil may also form an excessively thick protective coating on the engine components and could lead to starvation due to the impeded oil flow. Lastly, using 10w30 oil may also defeat the primary advantage of the workability of a 5w20 engine in lower temperatures.

In such cases, it is best to comply with the specifications set by the user manual of the vehicle provided by the vehicle manufacturer and stick to using 5w20 engine oil in a 5w20 engine.