Motorcycle oil is hands down the most important component in your motorcycle’s engine. The main job of the oil is to keep your engine lubricated, stopping metal to metal contact, and running as it should, but how many of us know exactly what we’re putting into our bikes?
With all the different numbers and different ‘types’ of oil, it can be confusing stuff. Here’s a little explanation of what it all means…
Types of oil…
Crude oil is a naturally occurring substance found underground. It is formed from ancient plant and animal life that has decayed over millions of years under extreme heat and pressure. Crude oil is pumped from underground and then processed in a refinery, where a number of different oil products are produced – including petrol, diesel and what we know as engine oil. Impurities are taken out during the refining process and chemicals are added to make it suitable for use as engine oil, creating what we commonly know as a conventional or ‘natural’ lubricant.
This oil is recommended for smaller engines and engines that do not create a lot of mechanical pressure while running. Natural mineral oils also give good engine protection for the first few kilometres of running the engine in.
However, even though these oils are cheaper than the semi or fully synthetic oils on the market, the natural mineral oils don’t last as long. You need to constantly check your oil level and replace at the recommended intervals.
Synthetic
Fully synthetic oil is man-made from a series of chemicals blended in a factory laboratory. Synthetic oil can be manufactured to have different properties that improve its lubricating ability. The processing of synthetic oils can be very expensive.
This oil is deemed ‘the best of the best’ and should be used in high-performance motorcycles such as superbikes and race bikes, high revving machines which produce high specific outputs and a bigger stress on the engine.
Synthetic oil is manufactured and developed to have a long life. The oil doesn’t degrade or break down as quickly as natural or semi-synthetic oils as well as providing the best lubricating performance which won’t break under pressure.
Semi-synthetic
Finally, we have semi-synthetic oil which, at its most basic level, is a mixture of both natural and synthetic oils.
This oil is recommended for motorcycles with engine capacity of 250cc or above – bikes that produce plenty of horsepower but without much stress.
It is also advised that you switch to the SS oil after you have used the natural oil to run in your engine. In general, it’s the all-rounder of engine oils, which offers good lubrication for all but the highest-performing engines.
Now you know what type of motorcycle oils are on the market, next you need to know what you’re looking for. Motorcycle oil comes in different grades or classifications.
Car versus bikes
You’ll notice that oils for motorcycles are marketed separately from car oils, but can you use car oil in your bike engine?
Well, it’s best not to (and definitely don’t use an ‘energy conserving’ car oil). Motorcycles have slightly different technology to cars, and have different stresses placed on them. Cars tend to have much longer service intervals and much bigger oil capacities, they also don’t rev as high as most motorcycles and most bikes have wet clutches (where the clutch bathes in engine oil). Bike oils are formulated to take account of all of this and often have different additives to oils designed for cars, which is why it’s best to use a motorcycle specific oil.
Motorcycle oil grading system
The terms 10W40 or 15W50 can be confusing to the average motorcycle rider, that’s why so many of us rely on mechanics to advise what the best oil is for your bike. So, let’s break it down…
When looking at the oil grade information, take note first of the first number – we’ll use the most common 10W40 as an example.
The 10 and the 40 stands for ‘multigrade’ while the W stands for ‘winter’ it’s that simple!
What’s winter got to do with it? Well, the grading is all about oil thickness, or viscosity, at various temperatures, because as oil gets thinner as it gets hot.
For a 10W40 oil grade, the 10 and the 40 is referring to temperature. The number 10 represents viscosity (thickness) at low temperature while the number 40 means that the oil will hold its shape and viscosity within the 40°C range.
Lower viscosity (thinner) oils can create less internal drag when running through the engine, which means that a race team may use an expensive, fully-synthetic 5W40, oil to extract a few more horsepower from their engines. but as an everyday rider, it’s always best simply to follow what the handbook says. Manufacturers develop their bikes around certain types and thicknesses of oil and it’s best to use what they recommend, as the wrong oil may cause the engine’s components to wear out more quickly than they otherwise would.
What oil is on the market and are they worth it?
When walking into a motorcycle garage you are normally greeted with bottles of oil, all from different manufacturers. Rock Oil, Shell Advance, Silkolene, Motul and Castrol are among the most popular in the UK, but is there any difference between these oils? Is it worth spending more money on one brand over another?
Arguably, no, it doesn’t although it, of course, matters about what grade or the type of oil you put in your motorcycle, and the owners/workshop manual normally tells you what oil is required for your bike.
As with most things in life, you get what you pay for. The cheap engine oil you find in supermarkets is basic and unlikely to be designed for your motorcycle, but move up to a specialist oil and although some brands are more expensive than others, the difference between them is often minimal. Using 10W40 Silkolene oil compared 10W40 Rock Oil is unlikely to give you an advantage as a road rider, even though there will be subtle differences in the formulation which may lead to tiny variations on the dyno.
Checking oil levels
Checking the oil level on your bike is simple. Motorcycles either have a dipstick or an oil sight glass. Whatever your bike has, there will be two markings that indicate the minimum and maximum oil quantity.
Make sure your oil level is between those markings, but towards the maximum level.
If you need to adjust your oil level, you do so by adding or removing some oil. As always when carrying out work on your motorbike, it’s best to use the handbook for guidance.
Knowing how much oil to put in your bike
The quantity of oil that is in your bike is crucial. Too little oil can lead to catastrophic engine issues. Too much oil will cause high oil pressure and can also cause damage to your engine. So how do you know how much oil your bike takes?
On most bikes, it will tell you how much oil is required on the side of the engine casing. For example, a bike could have 2300ml stamped on the casing, which means the engine holds 2.3 litres of oil.
If there is no marking to say how much oil is required, it will tell you in the workshop manual. More often or not you will replace the oil filter at the same time as carrying out an oil change but if you’re not changing this check the handbook, as most likely less oil will be required.
So, the next time you head down to your local motorcycle workshop for oil, you’ll now know what you’re after!
