Can I use 15w40 ENGINE OIL instead of using 15w50 in Royal Enfield?

Engine oils cater to a wide range of vehicles. They are needed to lubricate the engines of various bikes, rickshaws, cars, trucks, heavy vehicles, etc. Royal Enfield is one such bike that is slowly gaining popularity all over. As grand as the bikes and their different models are, their engines are also high in maintenance. Royal Enfield owners often ask people ask – Can I use 15w40 engine oil instead of using 15w50 in Royal Enfield?

The answer is no. 15w-50 is a more suitable engine oil for your Royal Enfield than 15w-40. As 15w-50 is the recommended viscosity grade for the Twin Spark engines that are used in their models. Both have the same viscosity but 15w-50 is more resistant to higher temperatures than 15w-40. 

Why is 15w-50 better than 15w-40 for Royal Enfield?

As is advised by the bike manufacturer, 15w-50 is the suggested engine oil for their recent engines. The engine oil viscosity grade provides superior engine protection against wear and corrosion. It makes for a smooth riding experience for your Royal Enfield.

 The thickness and the viscous property of the lubricant are essential in resisting the effect of thinning out at higher temperatures. The torque and pickup for this oil are also best as compared to 15w-40 or 10w-40. 

It ensures that the oil will be resistant to burning out in hotter conditions as well. Thus, choosing 15w-50 is the best way to go

reasons why 15w50 is better than 15w40 for royal enfeild

What is the difference between 15w40 and 15w50?

15w-50 as an engine oil lubricant is slightly more viscous in viscosity as opposed to 15w-40. As mentioned above, the oil is fit to provide good engine lubrication as well as great protection. 

Furthermore, the oil is also known to have a good drain interval. As per current norms, the oil change should be taken care of around every 6000kms. On the other hand, 15w-40 is said to be more suited for diesel engines and used in a warmer climate.

After how many kilometers engine oil should be changed in Royal Enfield Classic 350?

According to the latest norms by Royal Enfeild, every 6 months or 5,000 km, whichever occurs earlier. The previous recommendation by the company was 3,000 km or 3 months. 

Is 15w50 thicker than 15w40?

Yes, the 15w-50 oil’s viscosity is more than the 15w-40. While they both have a similar low-temperature (W-Winter) oil viscosity, the high-temperature viscosity, which is indicated by only a number is different. 

According to the standards, the higher the latter number (50), the thicker is the lubricant. 15w-50 will perform better due to high viscosity at high temperature than 15w-40. 

Moreover, these grades are considered multigrade oils which perform well no matter the seasons or conditions they are exposed to. 

What is 15w-50 used for?

15w-50 has a viscosity grade of 40. It is thicker and heavier as compared to 15w-40. It has been recommended for engines that have high performance. Most essentially used in motorsports, they are equipped to operate under heated and stressful conditions.   

What is 15w-40 used for?

Usually, these oils apply to heavy-duty diesel engines such as farm tractors, trucks (over the road), diesel equipment (off-highway), turbo-charged engines and gasoline engines as well as light diesel trucks. 

What problem creates if I replace 15w40 oil with 15w50 oil?

Using engine oils other than 15w-50 might lead to:

  • Decreased Engine Protection 
  • Overheating of Engine
  • Often Engine Oil Level Will Be Decreased
  • Potential of Smoke from Exhaust
  • Emission Gases Will Increase
  • Spark Plugs Changes are increased

    The owner manual mentions that if you use non-recommended oils, it can cause considerable damage to the engine moving parts. It will influence and affect the performance of the motorcycle along with voiding the warranty.


As per the Royal Enfield owner manual, 15w-50 is the engine oil you should be using for your motorcycle. 

Ensuring you’re using the right engine oil will get smooth and guaranteed performance from your engine. It will offer the required protection, avoid change in colour of engine oil by over heating and keep the temperature inside cool. Overall, it will encourage a better riding experience for you!

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