Oil is the lifeblood of an engine. Not enough and it will seize, too much and you run the risk of bursting a seal or gasket. Get it right, and an engine will run forever.
I know it sounds like a stupid question, but why do we even need oil in an engine? The quick answer is friction. Metal doesn’t like coming into contact with other pieces of metal. When this happens, there's a lack of lubrication, and what you get is heat and lots of it.
Heat makes components expand, and expansion either leads to component failure or seizure. Oil creates a microscopic barrier between moving parts that dissipates heat and keeps everything moving.
Viscosity or resistance to flow is how we measure the thickness of oil. And if you ever wondered what the W represents in 10W-40, it stands for winter. In other words, the fluid’s resistance to flow in zero degrees Fahrenheit.
Ok, so we know what it is and why we need it, but what happens when we don’t change it? All motorcycles come with a manufacturer’s recommendation for oil change periods. Calculated either by mileage or time interval. For example, the owner’s manual may recommend a change every 5000 miles or every year.
Over time, engine oil breaks down. Just think about it for a moment. A Yamaha R6 at full throttle makes 16,500 revolutions per minute, that means its crankshaft does 275 rotations per second. Subsequently, the oil gets a total battering.
Over time, oil is continuously heating and cooling. This factor, together with the crushing effect of components using it as a barrier, and contaminants from metal particles or combustion, break down its molecular structure. This process turns it to treacle.
By the way, if you’re now thinking, hmm, I don’t do the annual mileage as per my manual, so why do I have to change the oil if it isn’t doing the work?
Well, simply because, if your bike is just sitting there doing nothing or your sporadic journeys are short, then the oil never reaches its working temperature. When this happens, condensation can develop.
So, why don't water and oil play nicely together? Water molecules are polar and attract each other, whereas oil molecules aren't, so they prefer to stick to their kind too. Also, water is denser and prefers to lie underneath oil.
Last but not least, if you’ve got carburetors, fuel can find its way via the combustion chamber and into the oil, creating all kinds of mischief.
Ok, enough of all the tech stuff let’s get our hands dirty. I did intend to walk through the oil change on a particular bike, namely mine. But as the same basic steps apply to virtually every motorcycle out there, I've decided to keep it none specific and assume that this is your first rodeo.
Make yourself a cup of coffee. Then chill out with your owner's manual and read the oil change section. You need to know what oil it recommends. How much your bike requires and importantly, if you need to remove any parts to access the drain plug or filter.
It should also tell you what tools you need to perform the job. If it conveniently glosses over that, check it out online. It is also a good time to learn about any known issues.
Now is also a good time to find a container to catch the oil. Top Tip 1; make sure it's big enough to take all the waste oil but shallow enough to slide under the bike. Top Tip 2; don't borrow a baking tray from the kitchen, your roast chicken will taste like old engine oil, forever.
You will also need a handful of clean rags, a funnel and a spare crush washer for the drain plug.
Get yourself to a store. It doesn't matter if it's online or a good old-fashioned walk- in with real people. It's usually a good idea to buy slightly more oil than you want because if you are like me, some is bound to spill. And of course, it's useful for top-ups later.
When it comes to the oil filter, don’t assume that an aftermarket version is necessarily going to be the cheaper alternative. OEM oil filters are usually competitively priced and very good at what they do.
In saying that, if you've done your blog homework and people swear by a particular brand for your specific bike, then go for it. Just don't go for the cheapest, and that goes for the oil too. Remember that old Shakespearean quote; ‘A crap filter and cheap ass oil, do not a happy engine make.’
While you're shopping, get some latex gloves too. Hot engine oil on fingers hurts. If you forget, check in the kitchen cupboard under the sink, there’s always a pair of Marigolds hiding in there.
Locate the oil drain plug and the oil filter. Give both components a once-over in case they're covered in crud and need a wipe. If either looks a bit gnarly, a quick spray of WD40 won't hurt.
To drain all the oil out of the engine, it needs to be close to working temperature, so take the bike around the block. If for some reason you can't, warm it up on the spot. Just be careful of exhaust fumes if you’re in a garage with poor ventilation.
With the engine warm and being careful not to touch the exhaust, take the drain plug out. Get it spanner-loose, and then undo the rest by hand, being careful not to get it all over you.
To make sure you get all of the oil, you need to release the pressure in the crankcases. You do this by unscrewing the filler cap (usually located on the right side of the engine). Make sure you’ve got some long nose pliers handy, in case it’s in tight.
If you’re still not convinced, it's all out, depending on where the drain plug is, either lean the bike over (if it’s on the side). Secondly, take the spark plug(s) out and crank the engine over a few times on the starter button (make sure it’s in neutral too).
Filter removal is up next, and there are some tools on the market specifically for this, but a strap wrench is usually all you need. If for any reason it won’t budge, do not be tempted to hammer a screwdriver into it. Wrap some sandpaper around the filter, trying again with the strap wrench.
With the filter out, inspect the thread (if the thread on the old filter is good, then the thread in the engine, is too. Also, make sure the old oil seal came out with it. Give the area a wipe with a clean cloth.
When all the oil has drained, inspect the drain plug. Mine is magnetized, so it catches any tiny particles of metal. Give it a good wipe with a cloth, and then throw it away, so you don't transfer metal fragments on to anything else.
Inspect the crush washer; it may be aluminum or copper. If it looks ok, just reverse it and re-tighten. If it’s too chewed up, fit a new one.
Some of the older and larger bikes may have a secondary crankcase filter. It will tell you this in your owner’s manual. So, if it does, now is the time to remove, inspect and clean it,
Be really careful tightening it up too, use a torque wrench if you have one, but if you do it by hand do not over tighten it. A stripped crankcase thread will make you very sad and the nearest repair shop considerably richer.
Take the new oil filter and wipe the oil seal with a little oil. At this point, some people say you should charge the new filter (fill it with fresh oil), but it's not critical. Once again, be careful tightening up. Remember, there is only supposed to be enough pressure on it to distort the oil seal, not squish it.
With the filter and drain plug back in place, use a funnel to refill the engine, via the filler cap. Make sure you know how much it's supposed to hold. In other words, don't keep going till it starts to overflow.
Once you’ve filled it with the right amount of the correct oil, screw the filler cap back in, start her up and just let her tick over for a minute or so. Kill the engine, and check the drain plug and filter for leaks.
If it’s all good, put the bike in a level position so you can check the oil level. It might be via a sight glass in the crankcase or a dipstick on the filler cap. Too low? Top it up, a little oil at a time, be aware it takes a while to settle in the sump and give you a true reading.
Don’t panic if you over fill it either, just partially undo the drain plug until the oil starts to trickle out. Keep checking until it's right, and do not forget to retighten the drain plug!
And that pretty much is that. Rocket surgery it isn't. Just make sure you prepare everything you need before you start, including the spare crush washer and peripheral stuff like clean rags, etc. Take your time, and double check you’ve re-tightened anything you’ve undone.
The video below will demonstrate the process to help you visualize it
Last but not least, dispose of your old oil sensibly. Providing, of course, you haven't kicked over the container and are now slopping around in black gold.
Master the art of changing your motorcycle oil and filter by following these simple steps, and you will always have a happy engine!