Thursday 3 December 2015

Motorcycle Engine Oil - 101

This post is a beginner/intermediate-level introduction to engine oils. The concept of engine oil and its use is the same for all possible types of engines; may it be a motorcycle or a propeller-type aircraft and of course anything in between (e.g. car?!). Cars are the most common type of motor vehicle in the world and hence most of the information on internal combustion engines or associated products (like motor oil) found on the internet is to do with cars. In this post, I have tried my best to explain the concepts/details about engine oil, keeping motorcycles in mind. However as one can presume, most of the informative videos/animations I could find online, to explain a particular point, are mostly based on car engines. This is really not an issue though, as long as the subject of discussion is about basic properties and the use of 'Engine Oil'. Still, you can find some videos and animations shared in this post, which are specifically created for motorcycles. This will not only help you understand how engine oils work but also will enhance your general knowledge of the internal working of a motorcycle. Having said that, do keep in mind that the videos and other information (especially from the external sources/youtube) shared in this post belong to their respective publishers/authors and are possibly copyrighted. Also based on only the information given in this blog, you shouldn't be trying out anything with your motorcycle which may harm the engine or the vehicle as a whole. In such case, nobody but you would be responsible for the same. Now with the disclaimer out of the way, without further ado, let's get cracking.

Why does my motorcycle need engine oil?

Our motorcycles are driven by 'motors', which are nothing but a form of internal combustion engines. Simply put, it is a collection of mechanical parts which operate together to generate rotational power by burning a mixture of fuel and air. Now when I say mechanical parts operating together, that also means there would certainly be some form of physical contact between various parts which are mostly made up of metal (e.g. iron or other forms of alloy). Let's call the interaction between the parts 'the rub'. Now if you imagine two metals rubbing against each other, you can guess that there will be some sparks coming out and there will be a lot of heat and then, eventually the contact points involved in the friction will end up with some sort of wear and tear. Now an engine has no other go, to operate it has to function as a whole, i.e. an assembly of hundreds of (or more) mechanical parts. Parts that roll on or slide over other metal components and based on the duration the engine runs for or the RPM it is ridden at, the amount of friction will vary.

Let us consider a bullet (cast iron) engine for example. Now when it is idle (say waiting at a signal and not giving any throttle), the engine is revving close to 1000 rpm, that is 1000 rotations per minute. If you look at a 4-stroke engine diagram/animation, you would know how the piston, main shaft, crankshaft, flywheel, valves, push rods, cams (and all other components of the engine), all work together just to complete one rotation cycle. Now multiply that by 1000 and imagine this happening in just 60 seconds. Which means roughly 16 rotations per second. Wow!!! I too was startled by this figure, the very first time I realized it. These are gems of an invention, aren't they?!! Now just to knock you off your seat, here is one more amazing fact:

MotoGP bikes reach up to 17000 RPM during the race. 

I know. it's quite difficult to imagine such a fast rate of movement happening inside those small boxy motorcycle engines, isn't it ?!! Why don't to have a look for yourself in the following video clip and decide.

BMW S1000RR: Overhead cams (operating valves) at 14000 RPM

I am sure you got the point now. With such kind of friction/interaction between metal components (various parts of the engine) put inside a metal container (engine casing), imagine the kind of heat it must be generating and the level of catastrophic wear and tear it can cause if it had to run dry (read along and shortly you will know what it means). Now to keep such a contraption in operating condition, a solution was required, which should be able to reduce the friction between metal parts to the minimum, which in turn will make the components generate less heat and reduce wear and tear.

To achieve this, a thick oil-based lubricant was invented, which is commonly known as 'Engine Oil' or 'Motor Oil'. It is a thick fluid created by adding synthetic components to the base oil. This lubricant was filled inside the crankcase so that all operating parts stays dipped inside it during operation. Also, there were channels and a pump to push it all the way up to valve heads (and cams). The engine oil circulates all around the engine (except inside the combustion chamber) and keeps all the moving components covered and hence avoiding metal-to-metal contact. During operation, when the engine starts to heat up, engine oil retains the thickness (i.e. viscosity) up to a certain temperature and carries the heat away as it flows through to the sump (a storage area at the bottom of the crankcase. This keeps the engine components lubricated and relatively cool at all times of operation. 

How does the engine oil work inside the engine?

Have a look at the following video, which puts the earlier explanations into some perspective and gives a visual answer to this question:

Importance of Engine Oil in motorcycles (compared to other 4-wheeled vehicles)

A very informative video on Engine oils (basic to advanced)

You would have understood by now that today date that almost all vehicle manufacturers (may it be cars or motorcycles) recommend multi-grade engine oil for all their vehicles. What multi-grade means is, the viscosity (or thickness) of the engine oil varies depending on atmospheric temperature, in different/extreme seasons (summer/winter). Before we get into multi-grade, let us first understand what mono-grade engine oil is. 

Mono-grade Engine Oil:

This is the earlier version of engine oil which comes with a specified level of viscosity and retains the same up to a certain level of the temperature range. Above which the oil thins out and below which the oil thickens beyond use, either way reducing the protection level. The issue with mono or single-grade oil was, in winters, during extremely low temperatures the engine oil would thicken further and at times become like semi-solid wax, making it difficult for the engine to start. Again in peak summer, a single-grade oil will lose its viscosity once the temperature around gets hotter than the standard operating temperature specified for the oil. So to deal with these 2 extreme weather conditions, manufacturers started using two different single-grade oils, one during summer and one during winter. This means as a vehicle owner you had to get the oil changed to better suit the season you are going to be riding in. 

In the present day mono-grade engine oils are used in commercial or special cases where the environment the engine is intended to perform, doesn't vary much in temperature.

PS: I am trying out a mono-grade engine oil on my vintage motorcycle currently. I will try and post an update on the experience in near future.

Multi-grade Engine Oil:

Single-grade engine oils were the thing until a technological breakthrough was made and a new type of motor oil was developed, called multi-grade engine oil. This had the amazing property to have a lower viscosity when the temperature outside was low and achieves a predefined level of viscosity (i.e. gets thicker) when the temperature increases up to a specified range. This may sound strange contradicting the usual concept of physics, but this was made possible by introducing some form of polymer into the base oil. When the temperature increases, the molecules of the polymer expand, in turn thickening the oil and increasing the viscosity. So there you go, now you know how it all works.

Engine oil viscosity explained in detail

What do those numbers on an engine oil container mean?

Most brands of engine oil you would come across in the market today (2015) would be some form of multi-grade engine oil. In India (and in almost any other country),  if you walk into an automobile spare parts store and pick up a can of motorcycle engine oil in hand, it would have something like SAE 15W 40 (4T) written on it. Here is what it means:

SAE   Society of Automotive Engineers

15   Lowest operational temperature range

W    Winter

40   Highest operational temperature range

4T   Suitable for Four Stroke engines

As a thumb rule, the following are the operational temperature range for various rated oils:

Informational video from Motul explaining viscosity levels and their corresponding use

Other than SAE, here are a few other international motorcycle engine oil standards you may find:

JASO: Japanese Automobile Standards Organization

API: American Petroleum Institute (no formal approval process exists)

ISO: International Organization for Standardization (no formal approval process exists)

What is this synthetic engine oil that I am hearing about lately?

Depending on the type of base oil used, engine oils can be broadly categorized into the following types:
  1. Conventional Mineral Oil (most widely used)
  2. Synthetic Engine Oil
First and the traditional category of base oil is developed from petroleum-based crude oil. Synthetic oil is basically a highly processed form of crude oil (and some parts of it chemically manufactured), which is more refined than mineral oil and supposedly possesses higher capability and performance. Synthetic lubricants are more expensive that their conventional counterpart. 

Another variety is slowly making becoming mainstream, called Semi-synthetic lubricants for motorcycles. Which is nothing but a blend between the main two types of base oils, giving some benefits of modern synthetic lubricants yet costing slightly higher than mineral oil-based lubricants.

More on synthetic engine oils can be found here :

One point to note here is, synthetic engine oil is the next big thing in the automobile consumer market and hence has a huge revenue generation potential. This is the reason you would find all big manufacturers (Mobil, Valvoline, Castrol, etc) are using most of their marketing budget to promote this product, this doesn't necessarily mean for all motorcycles (say vintage or iron barrel like Royal Enfield cast iron models) synthetic is a good idea. The reason for this is beyond the scope of this post, so I will leave it here. Maybe when I get to write about what engine oil I use for my motorcycle, I can shed some light on that.

Does engine oil need to be changed at all?

The two major responsibility of the engine oil is to 1) lubricate all parts of the engine and avoid metal-to-metal contact (e.g. piston rings, cams, etc) 2) carry the heat off the components during circulation

Now during the day-to-day operation of a motorcycle, the engine oil is exposed to a lot of heat, and over a while (say after the motorcycle has done 3000-5000 KMs or so), the oil starts losing its efficiency to lubricate, as well as to disperse the heat. This condition is further supplemented by the deposit of other particles like soot generated due to combustion, fine particles generated due to metal corrosion inside the engine, etc. All these factors together render the engine oil to be less effective to the point, where the engine's performance starts to deteriorate. Which in turn results in overheating of the engine, low fuel economy, etc. The following animation will help you understand, how the engine oil gets contaminated over a prolonged period of use:

How/why engine oil efficiency reduces over prolonged use

In the worst of cases, if due to dirty deposits if the path of the oil is restricted to a certain part of the engine, it may result in engine failure or much worst: in a totaled motorcycle. So for motorcyclists, it highly recommends changing the engine oil in the manufacturer's recommended duration (or mileage). Replacing old engine oil with new one, not only makes your engine run much smoother, it prolongs the life of the engine components hence ensuring a long trouble free life for your beloved two-wheeled beauty ;)

These days I use my motorcycle for long-distance touring only and the rest of the days it remains in parking. Usually, I forget to make a note of my odometer during an oil change. Instead what I do is, try to check the condition of the oil before a ride and if looks fine to me for enduring the distance I wish to cover, I continue my way with a spare bottle to top up from (if required). Else I replace the engine and clutch oil with new ones. This method I don't recommend this to newbies or if you have no idea what to look for in used oil. Not that I am an expert in this, but I have a fair idea from my experience with my bike, on how the oil looks like before I know that it won't do the job anymore. If and when I switch to a modern motorcycle in the future, I would possibly stick to the manufacturer's recommendation for the initial few years.

Is engine oil for motorcycles any different from that of cars?

Well, as you would have learned by now, in terms of the basic properties of the engine oil, it's the same. However, due to changes to the engine design of cars from that of the motorcycles, there have been changes to the engine oils as well. Historically speaking, up until 1998 car engine oils were used as a base for motorcycle engines. As the cars had mostly different oil for the engine, clutch, and gearbox, as the technology evolved, the engine oils for car engines started to have more and more friction modifier agents. This was good for cars but was not good for motorcycle clutches and gearboxes. Modern motorcycle engines to be compact use a single case for the engine, clutch, and gearbox. Hence such car engine oils could cause the clutch to slip under higher revs. It may also cause issues with the motorcycle gearbox. This issue led the Japanese Automobile Standards Organisation (JASO) to come up with the following motorcycle-specific standards:

JASO introduced 2 ratings for 4-stroke motorcycle oils:
JASO MA – This was the standard for single unit engines where the wet clutch, gearbox and engine used the same oil. JASO-MA oils don’t contain friction modifiers.
JASO MB – This lower standard was for bikes that use separate oils for the engine, clutch and gearbox (e.g Harley Davidson’s and BMW’s).
Then in 2006, JASO introduced…..
JASO-MA2 – This specification was introduced in 2006 for  modern motorcycle engines. As well as being a higher standard of oil the JASO-MA2 approval means the oil is suitable for use in bikes with catalytic converts in the exhaust system.

Engine oil label with JASO. API and SAE ratings

Now it doesn't mean all non-JASO (e.g. SAE) standardized engine oils are meant for both cars and motorcycles. Irrespective of which brand you pick, each bottle/container of engine oil will specify which type of vehicle it is best suited to. It should also provide information on the type of additives it has and what are the possible benefits. So while selecting a particular engine oil, do read the information on the container.

I hope the information provided here was educational for you and you learned something, which you didn't know about engine oils today. In my opinion, from a motorcycle rider's perspective, this much background knowledge about engine oil would be more than sufficient for you. However now as you have learned how important engine oil is for the heart of the motorcycle (i.e. the engine), you might feel like going through the user manual again. And I highly recommend you that to better understand the needs for your specific make/model of the motorcycle. Lastly, I am closing this post with a few links to some more relevant videos and articles on this topic, which might be of interest to you.

5 Engine Oil Myths:

Don't Destroy Your Engine With Bad Motor Oil:[Video]

Choosing Engine Oil (with details on API S/C standards):[Video]

Update[18/11/2016]: Finally I have run out of Veedol HDB 50 oil and am not able to procure any from the Veedol dealer in Bangalore. So in my pursuit of the next engine oil, am trying out an unusual 20W50 CNG grade oil which is meant (as per the information on the can) for a 10,000 KMs service interval. Using the motorcycle every day to the office for the last week and planning to continue riding. Traffic is testing my clutch cable as well as my patience every day. Regarding the oil, I will update you after a long ride. Meanwhile, I found this video useful for sharing:

Until next time.

Ride Safe & Ride Far, 



Ash Green said...

Thanks for such a nice content. Apppreciate it :)
If anyone interested similar one's have a look here the thanks

Ash Green said...

Thank you so much for such an informative piece of information :)
If anyone interested similar one's have a look here
more @


Laura Bush said...

Your blog contains very useful and informative ideas about used engine of vehicle. as we provide Used Acura Engine at affordable prices. for more info visit our website.


Your post content very informative and good attractive introduction thanks

imlanguages said...

I'd like to express my gratitude for writing such a helpful article about Quality Used Transmissions.This article provided me with some useful knowledge. Thank you for sharing that. Keep up the good work.

KASHAF said...

Peloton shoes Thanks for a very interesting blog. What else may I get that kind of info written in such a perfect approach? I’ve a undertaking that I am simply now operating on, and I have been at the look out for such info.