10w30 Vs 20w40: Which Engine Oil Should Choose?

20w40 vs 10w30

Both 10w30 and 20w40 are multi-grade oils that change the viscosity level at varying temperatures. They provide the engines with certain advantages and disadvantages depending on where you are using them.

So, if you don’t know the difference between 10w30 vs 20w40, then let me help you out. I have decoded all the tough and confusing details so that you understand which of them should you be using.

Let’s start with the explanation of these oils.

What Is 10w30 Engine Oil?

10w30 is thin, synthetic engine oil that would flow smoothly at low temperature. The viscosity of this multi-grade engine oil is 10 when it’s cold and 30 when it’s hot. Since it has a lower W rating, you would find it best for lower temperatures.

Vehicles with petrol or diesel engines can use 10w30 oil as it would perform great in such weather conditions.

Read also: 10w30 Vs 30w oil – Details Comparison.

Advantages Of 10w30 Oils

Quick Start

10w30 engine oil has a great protective coating that prevents it from getting thickened, helping to flow quicker. It comes with incredible thermal stability that helps enhance cold start performance.

It Lowers Drag

This thin oil features high-molecular-weight polymers that act as drag reducers inside the vehicle to improve the flow. With the oil flowing smooth, it avoids friction between the cylinder walls and the piston compression rings. As a result, it lessens viscous drag on the parts.

Prolongs Engine Life At Low-Temp

Because the oil works to prevent metal-to-metal contact, it ensures less energy loss and prolongs engine life.

Great For Modern Engines

Modern engines have been mainly designed with tighter tolerances than their predecessors. It helps modern vehicles work greatly when thin oils are used.

Disadvantages Of 10w30 Oils

Not Ideal For Tropical Regions

Since 10w30 oil will become thinner when there’s an increase in temperatures, it won’t provide ideal fluid film to the metal parts, which can result in friction.

What Is 20w40 Engine Oil?

20w40 is thick, synthetic engine oil that ensures proper protection of the engine components, especially at higher temperature.

The viscosity of this multi-grade engine oil is 20 when it’s cold and increases to 30 when it’s hot. Due to higher W rating, it’s recommended for vehicles running under high temperatures.

Since air-cooled engines get extremely hot when used in warmer weather conditions, you need thick oil like 20w40 to ensure adequate protection.

Advantages Of 20w40 Oils

Maintains Film Strength

20w40 performs great at maintaining film strength under high temperatures and load conditions. Hence, it ensures amazing protection for engines.

Delivers Great Sealing Effect

This oil helps in sealing the pistons better. It makes sure the surfaces of engine bearings are protected while providing engine efficiency.

Great For Old Engines

The gap between the tight mechanical parts increases when engines become older. The viscosity of 20w40 at high temperatures helps fill the gaps so it keeps the engine safe from damages.

Disadvantages Of 20w40 Oils

Not For Colder Region

The oil gets thicker as temperatures drop, which can put a major strain on the engine. It gets harder to make the oil flow across the engine, which leads to hard start. That’s why, 20w40 oil is not a great choice for running under low temperature.

Comparing 20w40 Vs 10w30


10w30 oil is ideal for low temperatures as it would flow quicker than the high viscosity oil. Meanwhile, it’s not suggested that you use this thin oil at high temperatures as it causes friction due to oil becoming thinner.

For higher temperatures, 20w40 makes an ideal choice. It offers the required film strength under high temperatures as well as helps protect the engine.

Car Uses

If your engine is aged, then go with high viscosity oil. It will fill the gaps between the parts and deliver required protections to them.

For modern engines, engines need low viscosity oil that will flow quickly throughout the moving parts to make them run smoothly.

10W30 Vs 20W40 Which One Is For You?

Both the oils have upsides and downsides depending on where you live. If you are using the car at high temperature, then choose 20w40 engine oil. The heat will make the thick oil slightly thinner, allowing it to flow smoothly while offering adequate engine protection.

10w30 is great but more suited for low temperature. It would become slightly thick but also help the engine start quickly when the weather is cold. Such low viscosity oil also offers smooth lubrication if you are using the latest engine.

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