Is It Normal for Motorcycle Engine Oil To Decrease? You May Be Surprised


Engine oil is very important when it comes to any combustion engine. Ensuring your motorcycle engine is properly lubricated can help it run for tens of thousands of miles. 

You understand how important it is to keep your engine lubricated and that is why you may have this question. 

 Is it normal for motorcycle engine oil to decrease? It is normal for motorcycle engine oil to decrease, but it has specifications. Engine oil decrease is usually caused by leaks or the burning of oil.  These things are normal to an extent but should be addressed if it’s happening excessively.

There are a few reasons why your engine oil level may be decreasing over time. Some of these things are considered normal wear and tear, but others could mean catastrophic engine failure. 

Reasons Why Motorcycle Engine Oil Decreases Over Time

Your engine oil is vital to the life of your motorcycle. It allows the engine to rev up to high RPMs reliably. Some cruiser motorcycles like Harley – Davidson only rev up to maybe 6,000 rpm, while other performance bikes like a Yamaha R6 may see up to 16,000 RPM! RPM stands for revolutions per minute that the crankshaft makes inside of a combustion engine. Understanding this will help understand why it is normal for some of the engine oil to decrease in a motorcycle engine.

The most obvious form of engine oil decrease is an engine oil leak. This can happen due to worn seals on a motorcycle’s engine. If you are concerned about your engine oil decreasing this is the first place to start looking. 

When you bring your motorcycle back in from a ride, let it sit overnight. When you check in the morning if you notice any drips or puddles under your motorcycle, this can indicate a potential oil leak. If the fluid is oily and possibly golden to dark brown you may have an engine oil leak. If you aren’t sure what it may be you can always show a motorcycle technician and they will be able to let you know for sure. 

Once you have verified that it is engine oil, begin to inspect the engine to see where the drip may be coming from. Some common areas to check are stator covers, engine oil filter seal, valve covers, and crankcase seals. You are probably doing some further research on this because you aren’t experiencing an engine oil leak, but your engine oil is decreasing.

Another reason why engine oil decreases is the burning of oil. As stated earlier your motorcycle engine gets worked hard! The higher you keep your engine RPMs the more work your oil has to put in to lubricate your engine. This causes temperatures to rise inside the engine and can cause the engine oil to deteriorate or potentially burn up. 

There are systems on your motorcycle that monitor oil pressure inside the engine as well. These systems can cause engine oil to be burnt through the exhaust if it is overfilled or pressures exceed specifications inside the engine. 

A common symptom of burning oil is needing to add oil in between oil changes. Smoke from the exhaust pipe is also an indicator that your engine oil is decreasing because it is literally burning out of the exhaust. If you’re having smoking issues from your motorcycle, check out our article “Why Is My Motorcycle Smoking? 4 Reasons And How To Fix It.”

At What Point Does Decreased Oil Indicate A Problem?

Each motorcycle manufacturer has certain specifications for how much engine oil can decrease in a certain time period. According to an article from Bell Performance, The majority of manufacturers consider one quart of oil in the range of 1,500 miles to be acceptable.  It should also be pointed out there are some performance vehicles that will consume a quart of oil in less than 1,000 miles and is also considered acceptable.” 

In order to understand how much your engine oil is truly decreasing, you can perform an oil consumption test. This will tell you how much oil your motorcycle engine is decreasing within a certain time frame. 

To perform an oil consumption test properly, you will want to change your air filter, engine oil filter, and engine oil in your motorcycle. Ensure the proper oil viscosity is used that the manufacturer recommends and it is filled to the correct level. Overfilling can cause oil to burn faster. While these seem like ordinary maintenance procedures they all need to be done to eliminate any variables that may interfere with oil consumption.

Next is the fun part, RIDE BABY RIDE! Drive your motorcycle for about 1,000 miles or so. Bring your motorcycle back into the garage and carefully examine your oil level. If you have an oil level indicator, make note of how much oil has been lost. 

If you do not have an oil level indicator to tell you how much you lost, drain the oil into a drain pan and put it back into the quart containers to see how much you lost. You can reuse this oil later assuming your drain pan is clean.

Once you know how much you have used, if it was more than 1.5 quarts it may not be a bad idea to get an opinion from a motorcycle technician about what is causing your engine oil to decrease. Tell them you have already performed an oil consumption test and watch their eyes light up because of your knowledge of motorcycles! 

How To Prevent Motorcycle Engine Oil From Decreasing

There are ways to prevent engine oil from decreasing. A lot of it will come down to your basic maintenance of engine oil changes. If you purchased a used motorcycle and are concerned it may be decreasing in engine oil rapidly the first thing to do is change the engine oil and filter. If engine oil is old and broken down it will burn easier because its chemical properties are gone and it will also wear out your engine faster. 

The next thing to do is change your engine air filter. This filter can become clogged or worse allowing contaminants into the engine and engine oil causing irreversible damage. 

Something you can try at no cost to you is changing your driving style. If you are constantly banging the rev limiter when driving your motorcycle this can cause it to use more oil. While it is fun to do this occasionally, doing it every time you ride will shorten your engine life and will decrease engine oil levels much more rapidly. Take your wrist out of the throttle a little more and see how much oil you save. 

As a last-ditch effort, meaning you have tried all these things above and have noticed no change and it is still losing more oil than specified, talk with your motorcycle technician and see what oil additives they recommend to extend oil life. There are many of them out there, some will yield better results than others.

Whichever method you choose, make sure your oil level stays at the specified level as much as possible. If it gets too low it can cause catastrophic engine failure. 

How Low Can Motorcycle Engine Oil Get Before It Causes Damage?

The best answer for this is you do not want to find out. Engine oil when it’s at the low indicator means that it can still function properly but you need to add some oil as soon as possible. If your engine oil level sinks below this it is possible it may have already caused damage to your engine. 

There are a few things that come into play though to determine this. Let’s say on your inspection before you go on a ride your level is below the low mark. The last time you rode your bike there were no weird noises or vibrations coming from your bike. The chances that damage occurred are slim but will only proceed to cause damage if not filled up to the proper level.

On the other hand, if your bike was acting weird, smoke coming from the exhaust, tapping or knocking noises were heard and the bike was vibrating abnormally, you probably have some irreversible damage done to the engine. Needless to say, it is still important to top that oil off to see if any of those conditions go away or if they stay consistent. If they stay consistent with the proper oil level, take your bike to a certified motorcycle technician before the damage gets any worse.

Keep an eye on your engine oil level my fellow riders. It can be the difference between a great day of riding or a bad day of tow trucks and shop bills. 

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