20w40 vs 20w50

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20w40 and 20w50 are multi-grade engine oils, preferable for modern engines. The difference in their viscosity is very subtle. But every difference counts when you are choosing lubrication for your vehicle engine. Both of these engine oils are ideal for petrol & diesel engines.

Therefore, it is a lucrative and efficient choice to pick either one of these oils. They assure superior performance, proficient cleaning capacity, thermal stability, and whatnot.

20w40 vs 20w50

Keeping all of these details in mind, the one thing you need to check at first is the compatibility of your vehicle with these oils. When you pass through that, you can go ahead and check the specifications of 20w40 and 20w50 oils to know which would be better for your car. To help you get more clarity upon it, here is our 20w40 vs. 20w50 article to help you make a firm decision.

Man looking under hood of car at roadside breakdown

20w40 Specifications

20w40 is one of the special multi-grade oils as its formulation of base oils, and balanced additives are superior. Therefore, it helps maintain the horsepower of your vehicle progressively. Also, it offers ideal protection to your vehicle’s engine from corrosion and rust.

Hence, the equipment life will increase, and the operating & service costs will reduce gradually. Not just that, but oxidation & thermal stability are ideal perks of using this engine oil.

The built-in cleaning feature of 20w40 oil is what helps in cleaning and controlling the build-up of sludge. Moreover, it also eradicates the dirt deposits from engine components, thereby keeping the engine highly functional.

The viscosity of this oil makes it an ideal pick for heavy engines. In fact, it has a low-temperature viscosity rating of 20, whereas it is 40 for the high-end or operating temperatures. The viscosity of this oil signifies that it is thick, for which the list of compatible vehicles is different from usual oils.

In addition, 20w40 is preferable for the off-highway industries. It means that the vehicles running within the construction, agriculture, and quarrying industries prefer this oil type. Also, for highway vehicles, you can consider using this oil in light or medium load-bearing trucks.

In addition to that, all the gasoline and diesel-powered engines or pieces of equipment requiring high-level performance must go with 20w40.

20w40 motor oil is also being used for 4-stroke motorcycles, and the results are promising. Furthermore, with its high viscosity index, the vehicles or equipment emit top-notch performance. Moreover, in the process of lubrication, this oil also takes care of the dirt dispensing attribute.

Ducati motorcycle engine

20w50 Specifications

20w50 is yet another efficient motor oil that provides high-performance in all compatible vehicles or equipment. Furthermore, it can clean and protect the engine components for a long time, thereby increasing the functioning life. Also, 20w50 is a good recommendation for diverse applications due to its proficient high-temperature properties.

Furthermore, this engine oil has the potential to keep away rust and corrosion from the internal engine components. Moreover, it offers consistent power in order to reduce the amount of friction loss. Hence, it provides an ideal balance between fuel economy and engine performance.

Also, the fluid film protection potential of 20w50 is stable at all the operating temperatures.

This oil reduces the formation of deposits within the components, which smoothens their motion. For example, your vehicle or equipment engine’s bearing and valve train parts require optimal lubrication to offer operational efficiency. Therefore, this oil has the ideal properties to give them robust protection.

20w50, the numbers within this oil-type represent its viscosity rating at different temperatures. Being a multi-grade oil, it has a viscosity rating of 20 at low temperatures. And for high temperatures, it has a viscosity rating of 50.

Furthermore, 20w50 is preferable primarily for old vehicles, but as they are formulated for high-loads, few of the racing engines use it.

All vehicles are not compatible with this oil. It is because using this oil in the wrong vehicle will result in reducing the functionality potential of its crankshaft. Moreover, 20w50 consumes more fuel and doesn’t contribute towards improving the fuel economy.

Therefore, it is not suggested for the modern or light-duty engines, as the thickness of this oil doesn’t help in less fuel consumption.

BMW car engine

20w40 vs 20w50


  • Both of these oils have the same low-end viscosity of 20.
  • Both are ideal cleaning agents for the engine components.
  • These oils offer better thermal and oxidation stability.
  • Both 20w40 and 20w50 are thick oils.
  • 20w40 and 20w50 perform the same in winter climates.


  • The high-end viscosity of these oils is different. For example, it is 40 & 50 for 20w40 and 20w50, respectively.
  • The flashpoint of 20w40 is 238 degrees C, whereas, for 20w50, it is 230 degrees C.
  • The pour point of 20w40 is -30 degrees Celsius, whereas, for 20w50, it is -42 degrees Celsius.
  • 20w40 performs better in hot climates in comparison to 20w50.
  • Also, 20w40 is more fuel-efficient in comparison to 20w50.

Major Distinguishing Factor

The major distinguishing factor between 20w40 and 20w50 is their viscosity index. For example, the viscosity index for 20w40 is 118, whereas for 20w50, the viscosity index is 130. Therefore, consider your vehicle’s specifications and check its compatibility with the oil type to pick the right one.

When To Use 20w40?

20w40 is suitable for the heavy off-highway industries, such as construction, agriculture, and quarrying. It is also preferable for light or medium-duty trucks that run on highways. Hence, consider all these applications to ensure that you do not use the wrong oil in the wrong vehicle or equipment. 

When To Use 20w50?

20w50 is slightly thicker than that of 20w40 and is preferable for old engines and, in some instances, for racing engines as well. If you own 4-stroke superbikes or cars with racing engines, then this oil is suitable for the purpose. Also, if you own any classic and old car that usually runs in a hot climate, then 20w50 can be the choice.

Final Verdict

Even though there are very subtle differences between 20w40 and 20w50, they are still impactful on efficiency and specifications. Both the oils offer near about the same performance in terms of temperatures. Therefore, the only factor for choosing one among them is vehicle compatibility.

Check that aspect, and compare the specifications to make a decision.