Differences between 5w40 vs 5w50 motor oil

About 5W40

5W40 stands for 5 is the oil viscosity at 0 degrees C while W represents winter and 40 is the viscosity at 100 degrees C. every engine requires an oil that is not too watery but also an oil that is viscous enough to enable it to flow through the engine without creating problems which may include overloading the oil pump and decreasing the oil pressure (Boffa et al., 2019).  It is recommended to use 5W40 for a new car. However, this entirely depends on where one lives because for hot areas like in Africa; the manufacturers usually recommend certain oil. Also, if one lives in Canada where the temperatures are relatively cold, a different type of oil would be recommended.  Always, the viscosity of the oil is usually the weight of the oil. Therefore, the higher the number, the thicker the oil. However, the numbers normally require some interpretation. Normally, the viscosity of the oil is dependent on the temperature meaning during the cold season; it is more viscous and less viscous when it is warm, and this could result in problems. 

A cold engine requires a lighter weight or less viscous oil since it can be difficult to pump a heavier weight. Unfortunately, as an engine warms up, normally the oil reduces in viscosity and as a result does not protect well. Therefore when one is at higher temperatures, they should get oil that will start out at higher viscosity so that when it warms up, it can work better. Oil companies have come up with multi weights oils to help solve this problem (Boffa et al., 2019).  Usually, these do not comply with any profile for viscosity. Rather, they behave as if they are oils of different weights made for different temperatures. Therefore, W40 behaves like weight oil operating at low temperatures, and as a result, it flows easily. When it is at high temperatures, it thus behaves like 40 weight oil and thus stays more viscous and as a result, provides more protection.

Generally, oils get thinner as they heat up. Also, the single grade oils become too thin when it gets hot, especially for modern engines and that where the multigame oil comes in. The idea is normally simple; it uses physics and science to prevent the base oil from becoming too thin when it becomes hot. As earlier mentioned, the number before W is used to refer to the rating of the viscosity of the oil and the number coming after W is the hot viscosity rating (Boffa et al., 2019). Therefore motor oil rated as 5W40 is the one which behaves as 5-rated single grade oil, particularly when the temperatures are cold. However, it does not thin away to more than 40-rated single grade oil when it becomes hot. Thus, the lower the winter number, the simpler and easier the engine will turn as it is starting in the cold climates.

The following are characteristics of 5W40

Fully synthetic

  1. It ensures that the engine is always protected from deposit build-up and wear
  2. Facilitates an excellent cold starting as well as fast circulation in cold or freezing temperatures.
  3. It gets to all the moving parts of the engine fast

About 5W50

It is full synthetic motor oil, and it helps keep a car’s engine new. It uses a race-proven tech which is suitable for extreme motorsport applications as well as driving conditions. Whether on normal or racing driving, it assists in offering a heavy-duty engine performance as well as protecting the engine while offering an impeccable driving experience (Esfe & Fouladi, 2019).  It has been made with a blend of extremely high ultra-performance synthetic base stocks strengthened with a particularly balanced component. As a result, it assists in offering a flexible mix of superior protection agents that offer excellent performance in various driving situations

The following are some of its characteristics.

  1. It has anti-oxidants which assist in improving oil life
  2. Protects as well as performs in and at low temperatures
  3. It prevents sludge build-up and deposits from facilitating a clean and long engine life
  4. The wide viscosity grade helps to offer a flexible mix of low and high-temperature protection
  5. The high-performance base stocks mixed with a particular well-balanced system of component brings about impeccable wear protection that is all around.

The application of 5W50

Its utilization of a balanced technology helps it to be suitable for different types of operating conditions ranging from mild to severe it can be comfortably used in

  • Several diesel and gasoline engine advancements
  • Operating conditions that range from mild to extreme
  • High-performance engines

However, it is imperative for a driver always to check and confirm from their owner’s manual to see the recommended viscosity grade as well as specifications required for their specific cars.

Differences between 5w40 vs. 5w50 motor oil

The main difference between the two is the velocity of the oils. Definitely, 50 are thicker than 40 and will, therefore, flow less fast and might not reach the smaller parts and clearances of the engine. Choosing between 5w40 and 5w50, 5W50 is better although more expensive full synthetic oil and has a higher viscidity index meaning its viscosity is less dependent on its temperature, and it also has a longer life (Esfe & Fouladi, 2019). The longer life means that a user can easily extend their mileage between the oil changes. As a result, this will protect one’s engine even when it is under extreme conditions.  When the two are at low temperatures, they will inhibit similar properties, however when at high temperatures, 5W50 becomes more viscous than 40.


5W50 is recommended as compared to 5w40 since it favors longer drives. Since the numbers stand for the viscosity of the oil when it is cold and hot, it, therefore, means that the one with a higher viscosity the oil normally takes more time to move in the engine.it is in such instances that it is advisable to choose 50 rating oil.  However, it is important to note going down cannot cause challenges since it only means that the oil will move around faster as cold starts. In hit parts, the higher which is 5-0 is preferred as it works better against the heat and it helps to protect against the cold.

In summary, 5W50 works best in hot conditions. It is also full synthetic, and it works efficiently between the numbers and 50. On the other hand, 5W40 has its advantages and can be used as an option in case one fails to find 5W50. Also, it is always imperative to use the oil that is recommended by manufacturers or owner’s manual.


Boffa, A. B., Hartgers, W. A., Hosseini, S. M., & Campbell, C. B. (2019). U.S. Patent Application No. 16/021,213.

Esfe, M. H., Abad, A. T. K., & Fouladi, M. (2019). Effect of suspending optimized ratio of nano-additives MWCNT-Al2O3 on viscosity behavior of 5W50. Journal of Molecular Liquids285, 572-585.