10w40 vs 15w50 Motorcycle Engine Oil – Which is Better?

As a motorcycle owner, choosing the right oil for your engine can be a daunting task. With so many options available, it’s easy to get confused and overwhelmed. In this guide, I will help you understand the differences between 10w40 and 15w50 motorcycle oil, and help you decide which one is right for your bike.

Motorcycle oil comparison is a critical factor in determining what oil to use for your engine. The motor oil viscosity is an essential aspect of engine performance, and it determines the oil’s effectiveness in protecting your engine from wear and tear. Understanding the difference between 10w40 and 15w50 motorcycle oil will help you make an informed decision.

This motorcycle oil guide will take you through the differences in viscosity, performance, and benefits of choosing synthetic motorcycle oil. By the end of this article, you will have the knowledge to choose which oil is better for your motorcycle.

Key Takeaways

  • Choosing the right motorcycle oil is crucial for your engine’s performance.
  • 10w40 and 15w50 motorcycle oil are popular options for motorcycle engines.
  • The motor oil viscosity is an important factor that impacts engine protection.
  • Synthetic motorcycle oil has several advantages over conventional oil.
  • Factors like weather conditions and riding style should also be considered while choosing motorcycle oil.

Viscosity is the thickness of oil at a given temperature. As temperatures increase, viscosity increases.

The 10w40 is considered to be less viscous at higher temperatures when compared to 15w50 oil. What this means is that the 15w50 will perform a lot better in higher temperatures.

With that said, regularly changing your motorcycle oil is without a doubt one of the best thing you can do since it helps keep the bike running as smoothly as possible. In this article we are going to explain the difference between 10w40 and 15w50 motorcycle engine oil. So, continue reading to learn more.

10w40 vs 15w50 Motorcycle Engine Oil

One thing for sure is that choosing the correct motorcycle oil can make all the difference in how well your bike performs. Selecting an inferior grade could cause your engine to overheat, potentially leading to serious damage.

However, it is safe to say that the 10w40 motorcycle oil is capable of holding its performance up to 40 degrees Celsius, while the 15w50 on the the other hand has the ability to hold it up to 50 degrees Celsius.

So, if it’s a case where you need a motorcycle oil that will keep your engine well-lubricated, 15w50 is an ideal choice. This oil has better temperature viscosities than 10w40 and is perfect for bikes running at high revs which need additional lubrication.

Read Also: 20w40 vs 20w50 Engine Oil 

Motorcycle Oil Grades

When it comes to selecting the right oil for your motorcycle engine, understanding motor oil grades is essential. The two most commonly used grades in the market are 10w40 and 15w50 motorcycle oil. In this section, I will explain the significance of these grades and how they impact engine performance.

Motor Oil Grades – What Do They Mean?

Motor oil grades represent the oil’s viscosity, which is its resistance to flow at a specific temperature. The viscosity is measured using two numbers, such as 10w40 or 15w50. The first number, such as 10w or 15w, represents the viscosity at low temperatures, while the second number, such as 40 or 50, represents the oil’s viscosity at high temperatures.

For instance, 10w40 oil flows more easily in cold weather conditions and maintains its viscosity under high temperatures. On the other hand, 15w50 oil is thicker at low temperatures, providing better protection in extreme cold weather and maintaining its viscosity under high temperatures, making it ideal for use in harsh weather conditions and high-performance engines.

It is important to note that using the right viscosity grade is crucial in providing optimal lubrication, reducing engine wear and tear, and improving performance.

10w40 vs 15w50 Motorcycle Engine Oil

As we’ve mentioned earlier, having the right engine oil is essential for the longevity and performance of your motorcycle. This lubricates and safeguards the moving parts in the engine from experiencing any form of damage.

Motor oils are classified into viscosities based on how quickly the oil flows through a calibrated orifice when tested at standard temperatures.

Viscosity of an oil determines its flow resistance; this can be either a beneficial trait or detrimental one, depending on how you utilize the substance.

There is no doubt that, multigrade oils offer superior flow characteristics at both cold and warm temperatures, behaving like low-VI oils to reduce engine starting effort while saving wear on battery and starter components.

Multigrade oils are often utilized on modern motorcycles; however, you can also opt for monograde oils if that’s what you want.

Types of Motorcycle Engine Oil

Let’s start by saying that there are lots of different motorcycle engine oils available on the market with each tailored for a certain bike model. Options include conventional, semi-synthetic, and blended oils.

  • Conventional oil – It is derived from crude petroleum that’s then refined to remove contaminants. This makes it a suitable option for older engines and bikes with smaller engine capacities.
  • Synthetic oils – It’s composed of high-grade synthetic compounds to improve performance and protect against engine oxidation. Furthermore, these oils tend to have fewer deposits forming.
  • Semi-synthetic or blended oil – This is a mixture of mineral oil and synthetic oil to improve its performance. Although more expensive than mineral oils, they provide better lubrication as well as temperature oxidation resistance.

Motorcycle engines produce a lot of heat, so it is essential to choose an oil that can withstand it. This is especially true during summer when ambient temperatures may reach much higher than expected and making lubrication with 10w40 oil difficult.

10w40 vs 15w50 Motorcycle Oil

While both 10w40 and 15w50 motorcycle oils are designed to provide engine protection, there are key differences between them.

GradeViscosityRecommended UsageBenefits
10w40Low viscosity at low temperatures, high viscosity at high temperatures.Standard engines, moderate temperature conditions, long rides.Improves fuel efficiency, quicker engine startup, reduces engine deposits, better wear protection in moderate conditions.
15w50Higher viscosity at low temperatures, high viscosity at high temperatures.High-performance engines, extreme temperature conditions, short rides.Provides maximum wear protection in extreme conditions, better lubrication in high-performance engines, reduces engine wear and tear, prevents overheating.

Synthetic Motorcycle Oil

In addition to conventional oil, there is synthetic motorcycle oil, which is formulated to provide superior engine protection. Synthetic oil offers longer service life, better performance in extreme temperatures, and improved fuel efficiency.

Synthetic motorcycle oil also flows more easily in cold weather conditions, ensuring quick engine startup and providing better wear protection to the engine. However, synthetic oil is more expensive than conventional oil, making it less practical for some riders.

Ultimately, the choice between 10w40 and 15w50 motorcycle oil depends on your engine type, riding style, and weather conditions. It is important to follow the manufacturer’s recommendations and consult with a professional mechanic for expert advice.

Comparing 10w40 and 15w50 Motorcycle Oil

When comparing 10w40 and 15w50 motorcycle oil, it’s essential to consider their performance in various conditions. Both oils have their unique properties, which may suit different engines and riding styles. In this section, I will compare and contrast 10w40 and 15w50 oil to help you decide which is better for your bike.


The primary difference between 10w40 and 15w50 motorcycle oil lies in their viscosity ratings. 10w40 oil is thinner than 15w50 oil when cold but thicker when hot. This property makes it ideal for colder temperatures and startup situations. On the other hand, 15w50 oil is thicker when cold but thinner when hot, making it perfect for hotter weather conditions and extended rides.

Table: 10w40 vs 15w50 Viscosity ratings

Viscosity Ratings10w4015w50
Cold Weather1015
Hot Weather4050


While both oils have similar performance levels, they may be more suitable for particular engines and riding conditions. 10w40 oil is ideal for newer and smaller engines, providing better fuel efficiency and smoother rides. However, 15w50 oil is perfect for older and larger engines, providing more exceptional protection and reducing wear and tear.

Table: Performance Comparison of 10w40 and 15w50 oil

Performance Factors10w4015w50
Fuel EfficiencyHighMedium
Engine ProtectionLowHigh
Wear and TearHighLow

Usage and Recommendations

When choosing between 10w40 and 15w50 motorcycle oil, it’s essential to consider the manufacturer’s recommended usage specifications. Typically, older and larger engines require thicker oil, such as 15w50. Newer, smaller engines may perform optimally with thinner oil, such as 10w40.

Additionally, synthetic motorcycle oil has become increasingly popular due to its superior performance and extended lifespan. Synthetic blend oils combine synthetic and conventional oils, providing a balance between performance and affordability.


When it comes to choosing the right engine oil for your motorcycle, a little consideration goes a long way. The correct grade can mean the difference between an effortless ride and an unhygienic mess of red paint.

Beyond just considering temperature and terrain, you should also take into account ambient temperature and how often your bike takes a dip. Look out for grades that can withstand harsh elements while providing minimal service calls.

What does the term "SAE" stand for in SAE 30 engine oil?
Quiz Question Number 5