In this blog, we're going to be discussing motorcycle engine oil and answering some of the frequently asked questions about this vital element of your motorbike.

So what exactly does the oil in your motorcycle do? Well, it serves a variety of purposes but perhaps the most important is to reduce friction among the moving parts of your engine, which in turn reduces the wear and tear over time. It will also reduce energy loss, help maintain optimum performance, and help keep the inner workings of your bike clean by collecting debris and channelling it into the oil filter. If that wasn't enough, it will also help with cooling and even help to prevent corrosion!

That is quite a lot of work for one small liquid, so it isn't surprising that the make-up of engine oils can be quite complex, with a range of different types of oil available to suit different vehicles.

Now that we have talked about the purpose of your oil, let's look at some of the most commonly asked questions.

What are the different types of engine oil and which is the right one for me?

Having been over some of the vital roles oil plays in your engine, it shouldn't come as much of a surprise to learn that the composition of these oils has become more complex over the years. These days motorbike engine oils are going to be either fully or part synthetic and available in a range of viscosities in order to suit different engines with different requirements.

Ideally, the oil needs to be able to coat the inner workings of your engine like a film to provide optimum lubrication. If it is too thick then it will clog things up and increase temperature, if it is too thin then it will disperse too easily leaving more contact between moving metal parts. This can be further affected by the temperature your engine runs at and the amount of friction it generates as well as the general weather conditions you ride in.

With this in mind, you need to get the ideal type of oil for your own specific motorcycle and the best way to find this is to check your owner's manual. Aside from that, the internet is always hugely helpful if you are still unsure, and Halford's website even has a handy feature where you can enter your reg number and it will find the appropriate recommended oil!

What is the difference between synthetic and semi-synthetic oils?

Well as I mentioned earlier the composition of motorcycle oils are becoming more complex all the time. Manufacturers use synthetic additives to adjust the oil compounds in an effort to increase their efficiency within a motorcycle engine.

The difference between semi-synthetic and fully synthetic is simply the number of additives the oil contains. In short, a semi-synthetic oil is a 'purer' compound. In this particular case, the synthetic additives are designed to improve performance within motorcycle engine conditions so, generally speaking, fully synthetic oils are going to offer better protection and more efficiency for your motorcycle.

What does 10W-40 mean?

One of the most important aspects of engine oil is the viscosity (how thick it is). We already talked about how you need the right viscosity for perfect lubrication; the oil needs to be thin enough to fully coat the machinery in a fine protective film but thick enough that it won't easily disperse. This isn't necessarily straightforward either, as engine oil viscosity can be affected by temperature and most engines are going to heat up considerably during use, not to mention the effect of atmospheric weather conditions.

To help us out with this, motorcycle oils use a grading system that lets us know their viscosity and most modern oils use a multi-grade system that shows how they perform in both hot and cold conditions. In this example, 10W-40 gives both viscosity levels at low and high temperatures. The 'W' stands for 'Winter' which tells us the first number is the low-temperature viscosity - how the oil performs in winter conditions. The second number is the high-temperature viscosity.

What is the difference between 10W-40 and 10W-30 motor oil?

If we are comparing 10W-30 to 10W-40 then both oils have the same viscosity at low temperatures, but the 10W-40 will be thicker at a high temperature.

As a general rule, a lower first number means it can perform in lower temperatures and a higher second number means it can handle higher temperatures. I have included a handy chart that will show you the full range of atmospheric conditions the different grades can function in.

Can I use 10W30 in my motorcycle?

You need to use the correct grade oil for your particular engine to ensure it runs optimally so once again, be sure to check your owner's manual and choose the right one. Consider the weather conditions you will be riding in and take a look at the chart to see if this range is suitable for you.

What oil is on the market and are they worth it?

There are a variety of brands producing motorcycle oil with some of the more well-known makes including Putoline, Motul, Castrol, and Mobil. The price of these oils also varies and that comes down to the refinement process used and the number of synthetic additives.

Some of the most advanced oils are adjusted on a molecular level and have very expensive synthetic additives to ensure absolute optimum performance, but these oils are going to be more expensive due to the increased cost of production.

As to whether it is worth it, that largely depends on your needs. For example, when it comes to squeezing out maximum performance, a top-of-the-range superbike is going to feel the benefits of a premium fully synthetic oil more than a small scooter. Generally speaking, however, good quality oil is going to offer better protection for any bike, so it really comes down to you and your budget. Again, check around on the internet and get an idea of which brands get the best feedback for your model of bike.

What do the API and JASO MA specifications mean?

These basically mean that the oil has been tested and found to meet the standards set out by the American Petroleum Institute (API) and the Japanese Automotive Standards Organisation (JASO).

The API rating will have 2 letters, the first will always be an ‘S’ and the second letter will increase alphabetically depending on when it was produced. As technology has constantly improved, more advanced oils receive newer ratings with the current classification being ‘API SN’.

New oils usually cover older models just fine, but if you have a brand-new bike then stick with the latest oil classifications. There will usually be a suggested range of oils in your owner's manual, for example, my bike is a 2007 model and so oils with API classification ‘SE’ up to ‘SL’ are recommended. If your bike is very old, then you may need an oil suitable for classic motorbikes.

The JASO MA classification was created in Japan when motorbikes began producing very high levels of torque while using the same oil for their engine, gearbox, and clutch (one of the major differences between cars and motorcycles). It shows that the oil has been tested under various dynamic friction ranges (from 1.45 - 2.5).

In 2006, JASO MA was separated into 2 ratings based on the results of these tests - JASO MA1 and JASO MA2. JASO MA1 covers ranges of 1.45 - 1.8 and JASO MA2 covers 1.8-2.5. What does this all mean? Essentially it means that JASO MA2 is more suitable for engines with high torque and can be fine-tuned with synthetic additives to get the most out of these kinds of engine conditions.

When should I change my oil?

I'm going to sound like a broken record here but once again check your owner's manual. Your motorcycle will have its own service intervals worked out to let you know the best time to change your oil.

Even if your bike isn't seeing much use at the moment, oil doesn't last forever and the synthetic additives will wear out over time so you should still change it, typically after 12 months. The other time you would want to change it is if your oil levels are getting low, which brings us to the next question...

How do I check my oil levels?

This one is pretty straightforward, most motorcycles will have an inspection window, usually on the bottom right side of the engine. Hold the bike upright with the engine warm and take a look – the oil level should be between the full and empty markers on the window. Oil does evaporate at high heat so, if you're using your bike a lot it is definitely worth checking regularly to make sure it’s at the right level.

Knowing how much oil to put in

Yes, it is manual time again but if there is no clear answer in the owner's manual then you will simply have to add the oil slowly and check the inspection window to see when you reach the correct level.

Is cold starting an engine bad?

It definitely can be. If the temperature is too cold, then your oil will be too thick to flow properly and may leave some of the moving parts exposed in your engine which can cause increased wear. Some of the more advanced synthetic oils are designed to leave a coating behind after every use, so that could definitely help here but generally speaking if it is colder than the functioning temperature ranges of your oil it is best not to start the motor unless you absolutely have to.

If your bike is stored over the winter the only real benefit to starting it up in freezing temperatures is to charge the battery but, in this case, you are better off just removing the battery and maintaining it with a tender.

A really handy tool to own is an Optimate as it will drip feed the battery, ceasing the charge whenever the battery gets full so as not to overcharge it. You can read more on this in our how-to-fit an optimate guide. 

Do I need to warm my engine up?

As we have just talked about, high-quality oils should leave a thin inner coating behind in your engine to prevent wear on startup. You still want to give the engine time to get the oil moving around the system before you really open it up or that could be a fast way to cause damage to your engine. So the answer here is yes, allow a bit of time on startup for the oil to flow properly before you start pushing into high revs.

Can I use car oil in a motorcycle?

Hopefully, it is clear at this point that engine oils need to perform some vital tasks within your motorcycle and that these oils have been designed and developed specifically for this purpose. There are various differences between car and motorcycle engines and the way they run and that means even if you choose a car oil that has the correct viscosity, it will not have any of the synthetic additives designed for motorcycles and will not offer the same level of protection.

Think we’ve missed something? Or if you do have any other questions regarding motorcycle oil drop them in the comments below.

The summer riding season is approaching so, if you are planning on hitting the road soon make sure to check out our preparing your bike checklist.

If you are dusting your motorcycle off and getting back on the road for the warmer weather, make sure to get a motorcycle insurance quote direct with Lexham!