Motorcycle Engine Oil Grades: The Definitive Guide

Motorcycle Engine Oil Grades: The Definitive Guide
Motorcycle Engine Oil Guide

Different engine oils have different oil grades.

This is a complete guide on:

  • What engine oil grades are
  • What does the grade notation mean
  • What are single grade oils and multi-grade oils
  • Which engine oil grade to choose for your motorcycle

The motorcycle engine oil keeps the engine running and working in good condition by lubricating and cooling the engine components.

However, if the oil grade used is not right for the engine, then the lubrication will not be sufficient and the engine can overheat.

That’s why, understanding engine grades is important when using an engine oil in your motorcycle.

Let’s get started.

What Do Engine Oil Grades Mean?

An engine oil grade refers to the viscosity levels of the oil rated by the Society of Automotive Engineers (SAE).

In other words, oil grades are a simplified measurement of viscosity levels of the engine oil.

Viscosity is a measure of resistance to flow. It can also be described as the internal friction of a moving fluid.

Higher the viscosity of the oil, higher is the resistance to its motion due to its molecular breakup providing a lot of internal friction. The oil with high viscosity won’t flow easily. Similarly, low viscosity in the oil means low resistance and the oil will flow easily.

Different engine oil grades simply refer to different viscosity levels.

The desired oil grade or the optimum viscosity level depends on the make of the engine, the motorcycle condition, the climatic conditions of the locality, and the maintenance of the engine parts etc.

If higher free flow is desired, then you need to go for lower viscosity, and if the heat is not absorbed and cooled properly you need to increase the viscosity.

Oil Grade Notation

The motorcycle engine oil grade notation is denoted by “XW-XX”.

The oil is graded by measuring the time it takes for the oil to flow through a calibrated orifice at standard temperatures. The longer it takes for the oil to flow, higher is the viscosity and higher the grade.

The Society of Automotive Engineers (SAE) has established this numerical code system for grading engine oils based on these viscosity characteristics.

There are 2 sets of grading for the oils.

  1. Oil grading for cold temperatures (0W, 5W…)
  2. Oil grading for high temperatures (20, 30 …)

The common oil grade notation “XW-XX” denotes both the cold temperature as well as high temperature grading of the oil.

What Does An Oil Grade XW-XX Mean?

There are two parts to the engine oil grade notation.

The first part, “XW” refers to the viscosity grade for cold temperatures. The “W” here stands for Winter, referring to the cold temperatures at which viscosity performance is measured. The standard notation examples for the oil here are 0W, 5W, 15W, 20W and 25W.

The second part, “XX”, denoted after “W”, refers to the viscosity grade at high temperatures (usually measured at 100 degree Celsius). The notation examples are 8, 12, 16, 20, 30, 40, 50 and 60.

So, a 5W-30 oil has a weight of 5 during cold start, and a weight of 30 at high temperatures.

Also, a higher grade means higher viscosity. A 5W-30 engine oil will have a lower viscosity and better flow when compared to a 10W-40 oil.

Extending the above point, a 0W-30 oil will have higher flow at cold start than a 5W-30 oil. But both oils will behave same at normal temperatures.

Similarly, a 5W-30 oil and a 5W-40 oil will have same characteristics during a cold start. However, the 5W-40 is more viscous at high temperatures than the 5W-30 oil.

Single And Multi Grade Oils

Within engine oils, there are two classification – single grade oils and multi grade oils.

While single grade oils are useful only in climate conditions where the temperature does not change much, multi grade oils work in both cold and hot temperature conditions.

Single Grade Oils

Now, not all oils perform both at cold as well as hot temperatures. Some oils function only in cold climates and some only in normal and hot climates.

These motorcycle oils will have a smaller operating temperature range. The oils are generally designed for older motorcycle engines. Due to their low temperature range functioning, single grade oils are divided into two categories.

Winter grade oils – SAE 0W, 5W, 10W, 15W, 20W and 25W engine oils.

Non-Winter grade oils – SAE 8, 12, 16, 20, 30, 40, 50 and 60 engine oils.

Single grade oils are either suitable for cold temperatures (winter grade oils) or for hot temperatures (non-winter grade oils).

There is no overlap here, and the winter grade oils cannot be used for summer and similarly, non-winter grade oils cannot be used at cold temperatures.

Multi-Grade Oils

Multi-Grade Oils, on the other hand, have large temperature range and can work both at cold and hot temperatures.

Needless to say, multi-grade oils are the popular ones due to their utility across all the seasons. Most modern motorcycles use multi-grade oils for their engines now.

The viscosity grading of multi-grade oils will have two notations – one for the cold temperatures and the other one for normal or high temperatures. You will see the grades of multi-grade oils as 5W-30, 10W-30, 20W-40 etc.

In a 5W-30 multi-grade oil, “5W” refers to the viscosity grade at cold temperatures and “30” refers to the viscosity grade at normal and high temperatures.

The oil will behave as a single grade SAE 5W oil during cold temperatures and will behave as a single grade SAE 30 at normal and high temperatures.

Which Grade To Use For Your Motorcycle

When it comes to which oil grade to use for your motorcycle, the best resource is your bike’s owner manual.

The motorcycle owner manual recommends the suitable oil grade to be used in the engine.

Here are few examples of oil grade recommendation by different motorcycle manufacturers in their owner manuals.

Kawasaki Ninja H2 motorcycle owner manual recommends the engine oil grade to be SAE 10W-40.

Yamaha YZF models are recommended to use an oil grade of 10W-40 or 15W-50.

Here is the oil grade recommendation for Harley Davidson models in their owner manual.

So, if you are not sure which oil grade to use for your motorcycle engine, always check the owner manual for your motorcycle model.

Related Questions

How often should you change oil in a motorcycle? The frequency of oil change depends on the type of oil used in the motorcycle. Mineral oil should be changed every 2000 miles. For semi-synthetic oil, the frequency of oil change is every 5000 miles. And synthetic oil should be changed every 8000 miles.

How do you check engine oil level in a motorcycle? The engine oil level in a motorcycle can be checked by removing the oil gauge and checking the wet mark on the gauge. Ideally the oil wet mark should lie between ‘full’ and ‘low’ marks in the gauge.

What happens when motorcycle runs out of oil? Motorcycle engine will start heating up since there is not much oil to act as a coolant. If you still ride the motorcycle, then the consequence will be: burnt clutch plates, damaged piston rings, piston wear and damaged cylinder lining, impaired engine valves, hard shifting of gear, increased engine vibrations, and low mileage.