5w40 vs 5w50: Difference and Comparison

5W40 denotes the oil’s viscosity at 0 degrees Celsius, W denotes winter, and 40 denotes the density at 100 degrees Celsius. Every engine requires a viscous oil that is dense enough to move through the machine without causing issues such as overloading the oil pump or lowering the oil pressure.

Professionals recommend 5w40 under these conditions. 

5w50 is a fully synthetic motor oil that helps to keep a car’s engine in good condition. It employs race-proven technology ideal for extreme racing and everyday driving.

It’s constructed from a well-balanced component’s combination of ultra-high-performance synthetic base stocks.

Key Takeaways

1. Both 5W40 and 5W50 are multigrade motor oils with a winter (W) viscosity rating of 5, but 5W50 has a higher operating temperature viscosity rating than 5W40.
2. 5W50 oil provides better high-temperature performance and protection, while 5W40 offers better fuel efficiency and lower engine wear.
3. 5W40 is more suitable for normal driving conditions, whereas 5W50 is better for high-performance vehicles and extreme driving conditions.

5w40 vs 5w50

The difference between 5w40 and 5w50 is the high-temperature index, making 50w40 less stable at high temperatures and loads and 5w50 more stable. 5W40 oils have a somewhat lower viscosity and are synthetic lubricants, but 5W50 oils have a higher viscosity than 5W40 oils.

The 5W40 designation means that its viscosity range is on the lighter side of the spectrum. This is an advantage as it allows more effortless movement to components and less viscous drag during startup.

As a result, 5W40 has become the most widely used motor oil on the market.

5W-50 engine oil is designed for various applications, including motorsport, collector, and vintage automobiles, and demanding driving conditions, including hauling and high running temperatures. 5w50 provides increased cleanliness to help avoid engine sludge, which robs the engine of power and reduces fuel efficiency and performance.

Comparison Table

Parameters of Comparison	5w40	5w50
The oil’s thickness	The viscosity of oil with a 5w40 is lower than that of oil with a viscosity of 5w50.	The viscosity of oil with a viscosity of 5w50 is higher than the viscosity of oil with a viscosity of 5w40.
Speed	5w40 flows quicker than 5w50 and has a better chance of reaching the engine’s minor parts.	Because 5w50 has a slower flow rate, it may miss tiny components and clearances in the machine.
Kinematic viscosity at 100℃ (212 °F)	The kinematic viscosity of 5w40 at 100°C is 13.5 mm2/s.	The kinematic viscosity of 5w50 at 100°C is 17.67 mm2/s.
Price comparison	The cost of 5W40 is cheaper than that of 5W50.	5W50 is better, although being more expensive.
Viscousness	At high temperatures, 5W40 becomes less dense than 5W50.	At high temperatures, 5W50 becomes denser than 40, making it ideal for hot weather.
Freezing point	The freezing point of 5w40 is -32.8°F.	The freezing point of 5w50 is -40°F.
Life expectancy	5w40 has a shorter life expectancy than 5w40.	5w50 has a greater life expectancy than 5w40.

What is 5w40?

5W40 is a motor oil that moves more quickly to the active components and offers good lubrication at startup for automobiles. It is composed of a mixture of synthetic crude and petroleum. 

According to the SAE standard, this oil is suitable for automobiles that are driven frequently up to 15,000 miles per year. It is also used as a base stock for other kinds of oils.

This kind of oil provides lubrication at low temperatures and protects against wear caused by friction. For these reasons, it is used in the engine of an automobile during startup.

An automobile engine is started with the help of a gasoline or diesel-powered electric starter motor. This starter motor works by turning over the engine with great force until it builds up enough speed to run independently.

The gasoline-powered starter motor turns over the machine about 5-10 times before achieving a self-sustaining rate. If this process takes too long, the engine can damage heat build-up.*

5W40 motor oil provides lubrication for the engine parts when they are most vulnerable to damage from heat and friction. Automotive technicians recommend using 5W40 when the outside temperature is below 50 degrees Fahrenheit because it flows more readily in the cold than hot conditions.

What is 5w50?

5W-50 engine oil is a unique blend of motor oils designed for various applications, including classic, collector, and vintage vehicles and high-performance racing engines. The “5W” in the name refers to the oil’s viscosity – “W” stands for winter, which is the coldest season that engines have to endure.

5W-50 motor oil provides a “mild” performance level. This means it has characteristics that can help protect your engine in less demanding conditions and improve wear protection compared to “mild” 5W-30 motor oil.

As you move from 5W-30 to 5W-40, then to 5W-50, the amount of anti-wear additives increases, and the viscosity gets thicker. Each grade also includes additional detergents for cleaning deposits from the engine, particularly under heavy loads.

The “50” means that this is an SAE viscosity grade, where 50 represents the cold temperature rating on a 0 to 100 scale. The “5” illustrates the low end of the viscosity range (the higher the number, the thinner or more volatile the oil).

The “-30” means that this is 30 weight percent below 0 degrees F., equating to roughly 212 degrees F.

Main Differences Between 5w40 and 5w50 

1. 5w50 has a longer life expectancy than 5w40, but 5w40 has a shorter life expectancy.
2. Oil with a viscosity of 5w40 has a lower viscosity than oil with a viscosity of 5w50. In contrast, oil with a viscosity of 5w50 has a viscosity that is greater than oil with a viscosity of 5w40.
3. At 100°C, 5w40 has a kinematic viscosity of 13.5 mm2/s, whereas 5w50 has a kinematic viscosity of 17.67 mm2/s.
4. 5W40, on the other hand, becomes less dense than 5W50 at high temperatures. 5W50 becomes thicker than 40 at high temperatures, making it excellent for hot conditions.
5. Because 5w40 flows faster than 5w50, it has a higher chance of reaching the engine’s small parts, but 5w50 may miss microscopic components and clearances in the engine due to its slower flow rate.
6. The price of 5W40 is less than the price of 5W50. 5W50, on the other hand, is superior, although being more expensive.

References

1. https://www.sae.org/gsdownload/?prodCd=941980
2. https://www.sciencedirect.com/science/article/pii/S1385894715002326