15w50 vs 20w50

As an Amazon Associate we earn from qualifying purchases.

15w50 and 20w50 are interchangeable engine oils. It means that you can use both of these engine oils alternatively in compatible vehicles. The only important thing to consider is the operating temperature viscosity, which should be the same for any oils used interchangeably.

As the high-end viscosity of both these engine oils are at 50, you can use either one of them in place of the other. Also, these oils offer superior performance, optimal wear protection, and fuel efficiency to your vehicle engines.

15w50 vs 20w50

Even though both of these engine oils are interchangeable, they still have certain differences. Every bit of the difference between engine oils is worth consideration to maintain engine efficiency. And before you use 15w50 or 20w50 for your vehicle engine or equipment, you need to get an idea about their specifications.

Hence, this 15w50 vs 20w50 article will help you with the needful.

Dripping motor oil

15w50 Specifications

15w50 is one of the advanced engine oils with synthetic properties. The vehicle owners who expect seamless driving potential must go with this oil on priority. It is because 15w50 has racing technology embedded within it.

And the history of this oil type states its application in several motorsports, towing vehicles, and other critical service vehicles. Also, it is made up of an efficient bond or blend of synthetic base oils and ideal additive components.

In addition to that, the viscosity factor is yet another area that makes this oil even more proficient. The numbers within this engine oil, 15 and 50, denote the viscosity, thickness, and weight rating, at different temperatures.

For example, the number ‘15’ denotes the viscosity of this oil at low temperatures, whereas the number ‘50’ denotes the viscosity at operating temperatures. Due to the thickness of this oil, it is highly preferable for engines that transport or operate with heavy loads.

The heavy viscosity of this motor oil intends to offer dynamic lubrication to the engine components. Also, it helps clean out the sludge build-ups from the internal components and prevents them from coming back.

Irrespective of the driving styles, this engine oil offers ideal wear protection for all conditions. So, 15w50 is preferable for almost all types of vehicles that are used for high-performance output.

Currently, this oil is used in modern engines, with supercharging and turbocharging technology. Furthermore, the gasoline and diesel FI engines in light vans, trucks, and SUVs are also compatible with 15w50 oil. But, it is not a suitable oil for 2-cycle engines or aviation applications.

Rows of parked trucks

Still, it is better than most of the conventional oils in terms of handling engine stress scenarios.

20w50 Specifications

20w50 is yet another popular motor oil that is superior in cleaning the engine components, thereby maintaining the functionality. It is a fact that the gliding gears within the engine demand efficient lubrication to avoid friction contacts.

If the lubrication reduces, the gears and components will contact each other to increase the ratio of wear & tear. In this case, 20w50 is an ideal thick oil that can create enough lubrication in heavy engines.

In addition to that, it ensures that the contact between metal components is less, thereby controlling wear & tear. 20w50 motor oil meets the requirements and standards of API SL, enlightening its quality and efficacy. Furthermore, this multi-grade motor oil offers easy cold start-ups at low or winter temperatures.

Apart from that, it also has a good hold at high temperatures.

The viscosity rating of 20w50 is based upon the numbers over its name. For example, the number 20 denotes the viscosity rating of this oil at low temperatures, whereas the number 50 denotes the viscosity rating at high or operating temperatures.

Hence, this determines the thickness of this oil, for which it is preferable in racing engines on priority. Apart from that, some old classic vehicles, which run primarily in hot regions, can also use 20w50.

The thickness of this oil makes it an ideal choice for heavy load-bearing vehicles and industrial equipment as well. Therefore, you need to check the compatibility of your vehicle or equipment to the thickness of 20w50. It is an essential consideration because inappropriate thickness for a non-compatible vehicle can suppress the horsepower and engine functionalities.

Father and son fixing car engine

15w50 vs 20w50


  • The high-end viscosity of 20w50 and 15w50 is the same.
  • They both offer similar performance at high operating temperatures.
  • Both oils have the potential to clean the sludge build-up and promote dirt dispensing within the engine components.
  • These oils can be used interchangeably.
  • Both oils are designed for racing engines.


  • The kinematic viscosity of 15w50 at 100 degrees C is 18mm2/s, whereas for 20w50, at 100 degrees C, it is 20.5mm2/s.
  • The low-end viscosity of these oils differs from one another. For example, it is rated as 15, for 15w50, whereas 20 for 20w50.
  • 15w50 performs better at cold temperatures in comparison to 20w50.
  • The pour point of 20w50 is -42 degrees C, whereas, for 15w50, it is -39 degrees C.

Major Distinguishing Factor

The major distinguishing factor between the 15w50 and 20w50 motor oil is their viscosity indexes. For example, the viscosity index of 15w50 is 160, whereas, for 20w50, it is 130. The higher the index of viscosity, the better is the performance.

When To Use 15w50?

15w50 is preferable for modern turbocharge or supercharge gasoline and diesel engines. Apart from that, it is also preferable for heavy load-bearing vehicle engines that operate on or off highways. Therefore, check the compatibility of your vehicle with this engine oil type before deciding upon it.

Moreover, if your vehicle operates mostly in cold regions, then 15w50 has better low-temperature performance compared to 20w50, so you can choose it!

When To Use 20w50?

20w50 is preferable for the old classic engines and the super racing vehicles. The thickness of this oil helps such engines function proficiently over a long time, under different driving conditions. Therefore, it is an ideal alternative for 15w50 oil, and you can use either of it alternatively.

Final Verdict

15w50 motor oil, with a leading-edge in terms of low-end viscosity, is slightly more expensive than 20w50. Hence, it might be one important deciding factor for choosing one among these two for their compatible vehicles. Consider the specifications of them both for better enlightenment.

In addition to that, you can check the vehicle’s manual to get more details about the compatibility of the oil types with your vehicle.