Difference Between 5w20 And 10w40: Which Is Best For Your Car?  

Choosing the right oil for your car’s engine can be difficult. Most cars include a manual detailing the type of oil suitable for each engine.

Generally, there are four kinds of motor oil: synthetic, synthetic blend, high-mileage and conventional motor oil. The specifications for these oils are determined by the engine’s composition and current temperature.

Multi-grade oils 5w20 and 10w40 have different viscosities at different temperatures. So while you can use 5w20 during winter and cold start, 10w40 can be used when the engine runs and during summer.

This article will discuss in detail the differences between the two engine oils: 5w20 and 10w40. It will also illustrate scenarios where you can use both and which cars are best suited.

What Is Multi-Grade Motor Oil?

Multi-Grade Motor Oil’s properties are enriched to decrease its viscosity at low temperatures. As a result, a multi-grade oil is less fluid at low temperatures and thicker at higher temperatures when compared with monograde oil.

To classify motor oils by viscosity, a rating system was developed by the Society of Automotive Engineers. The fluid’s resistance against the flow is called viscosity. Thin fluids (like water) have a low viscosity, whereas thick liquids (like honey) will have a high viscosity. In the case of motor oil, as it is heated and cooled, its viscosity also changes.

Multi-grade viscosity oils can perform at wide-ranging temperatures. Moreover, it has a specific number that indicates its ability to pump and flow at lower temperatures (0⁰F) – the “W” is for winter. The lower this number is, the better it will perform in cold weather. For example, a 0W oil will flow faster and reach critical components quicker than a 10W or 5W oil. This is especially true when the engine starts up and in extreme cold.

The second number represents the engine’s viscosity value under operating conditions. This number is critical not only for the proper protection but also for the lubrication of your engine. The higher these digits are, the thicker your oil is — indicating how well it can successfully adhere to engine components at high temperatures (212⁰F). Therefore, a vehicle that recommends SAE 5W-20 oil can use SAE 0W-20 oil, especially in colder regions.

Understanding About 5w20 And 10w40

What is 5W20?

As mentioned earlier, the number preceding the “W” denotes oil viscosity at 0℉, and the numeral after the “W” signifies oil viscosity at 212℉.

Keeping that in mind, 5W20 oil, for example, has a viscosity of 5W at 0℉ and 20 at 212℉. Furthermore, 5W20 oil creates less drag that helps reduce fuel economy.

You can use this engine oil in different environments and on different vehicles. The oil is thinner than any other oil and can be used in cold temperatures, particularly in winter. In addition, 5W20 is a low viscosity product that will not freeze at low temperatures. This provides improved engine performance and lubrication in winter.

What is 10W40?

On the other hand, a 10W-40 oil generally has a viscosity of 10W at 0℉ and 40 at 212℉. At 40 °C, it weighs 10 pounds per gallon.

A 10W40 oil can improve your vehicle’s fuel economy. It can also protect your engine from wear and tear and reduce emissions. In addition, this oil is thicker than any other oil, including 5W20. Since it is thicker than other oils, it performs better in hot weather.

Also, it’s valid for vehicles with high mileage. It’s especially well-known for its superior performance in the engine section of any car. Although, you can’t use the oil in cold weather or very low temperatures.

Differences Between 5w20 And 10w40

Parameter for Comparison5w2010w40
Viscosity at 0°C510
Viscosity at 100°C2040
TemperatureMore benefcial in winter when temperatures are lowMore advantageous in warm weather at high temperatures
Startup performance at cold temperaturesGreaterLesser
Wear protection or leakage at operating temperaturesLesserGreater
Low-temperature flowQuickSlow
Proper usageMore effective in colder areas during winterUsed for high mileage and well-performed in warmer regions during summer
Useable automobileGasoline engines, light-duty petrol or passenger carsOlder engines, medium- to heavy-duty gasoline engines, diesel engines, and motorcycles
A Comparison Table between 5W20 and 10W40

Viscosity and Temperature

As mentioned, the code numbers indicate the viscosity rating at various temperatures before and after the “W.” 5w is the engine oil’s viscosity at a temperature below 0°C or when the engine is being started in the cold, while 10W is the engine oil’s viscosity at 100°C, or at operating temperature.

As shown in the “Viscosity Ranges of Modern Oil” chart below, the temperature range of a 5w20 multi-grade would be -35°C to +30°C and 10w40 would be -30°C to +40°C.

Type of motor oil

5W20 is available in both synthetic and conventional versions, whereas 10W40 engine oils are mainly synthetic blends.


The thicker the oil, the higher the second number. Furthermore, it measures oil flow at 100oC (212oF) at engine operating temperature. So basically, at machine operating temperature, 10w40 oil is thicker than 5w20. Generally, 5w20 is more effective in colder areas during winter. Whereas on the other hand, 10w40 in warmer regions during summer.

Proper Usage

The oil will flow faster through engine parts with lower viscosity at low temperatures. These types of engine oils tend to be thinner. This makes 5w20 oil more efficient than 10w40 for startup performance as well as  more resistant to extreme temperatures. Moreover, it protects against engine wear. 5w20 is recommended for engine protection and oil lubrication in winter and colder temperatures. Synthetic motor oil lasts longer than conventional oil.

At the same time, 10w40, a thicker oil, will provide better protection and seal leakage at higher temperatures. Like commercial vehicles, 10W40 is the best choice if you have heavier loads. The 10W40 thickness is specifically designed to handle the higher load and prevent metal-to-metal contact inside the engine. Therefore, when using high-mileage vehicles (10W40 Mobil 1 oil), it is recommended (even if they have used lower quality conventional oils).

Suitable automobile

5w20 engine oils are ideal for passenger cars, light-duty petrol, and gasoline engines due to their low viscosity.

For instance, Toyota, Mercury, Chrysler, Acura, Dodge, Lincoln, Honda, Mitsubishi, Ford, Mazda, and Jeep are all equipped with 5w20 specifications.

Additionally, BMW, Volvo, Jaguar, Saturn, Chevy, Nissan, Buick, Lexus, Pontiac, Subaru, Cadillac, and GMC also manufacture engines compatible with 5w20 oils.

On the other hand, 10w50 oil is more suitable for high-mileage cars, older engines, medium- to heavy-duty gasoline engines, diesel engines, and motorcycles.

Can I use 10w40 instead of 5w20?

Yes! However, remember to let it cool down enough so you won’t get burned. It will work best if you keep it close to the heat, but too much heat will cause it to fail. You can also use a 0W20 oil in a 5W20 engine.

Can I mix 5w20 and 10w40?                       

Yes, you can! However, it’s suggested to avoid doing so; different viscosity levels of the same brand may be possible, but mixing viscosity grades can result in a product with a different viscosity than what was in the engine initially or what was added.


1. What oil should I use for my car?

Your vehicle’s construction, model, and the climate you live in will determine the best oil for your vehicle. It is best to talk to your trusted mechanic if you’re unsure which oil to use.

2. Will thicker oil damage my engine?

Drivers may have used thicker oils to power their engines in certain circumstances. For example, a more viscous oil may be beneficial if clearances between components of an engine have decreased or become sloppy. Thicker oil provides a better lubricant layer between moving parts. In addition, some people have used thicker oil to prevent oil seepage from a leaky engine.

However, thicker oil is terrible for your engine when more viscous oil has a higher viscosity than what the manufacturer recommends. In addition, your engine is made with specific tolerances and spaces between moving parts. Hence, the recommendation to use a particular oil grade is intentional.

Additionally, the oil must be able to coat these surfaces. Still, it must also flow into the tight spaces of modern smaller, lighter engines and have tighter tolerances. So, in the end, pay heed to what the manufacturer recommends because it usually is the best oil for your engine.

3. What oil can I substitute for 5w 20?

Pumpability is reduced when temperatures fall below 0W and 5W. A 0W would flow faster than a 5W and could be used as a substitute. So, it is possible to replace the SAE 5W-20 with an SAE 0W-20.


After going through the difference between 5W20 and 10W40, we can’t say that one engine oil is better than another. It all depends on the vehicle’s make, temperature, location, and the viscosity rating.

5w20 oil has a lower oil viscosity, suitable for low temperatures and cold startup, while 10w40 oil is thicker and better for high-mileage cars. You can use these oils in the appropriate engine to increase efficiency and prevent engine wear. It is best to use the recommended oil viscosity by your car manufacturer.

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