What You Need To Know Before Changing the Oil in a Motorcycle

Dan Carney
Jun 27, 2018

Remember the crazy urban legend about M&M’s®? No, not the one about the supposed aphrodisiac power of the green ones. The one about Van Halen demanding the removal of the brown candies from the M&M’s® set out in their dressing room.

While it might seem like an example of over-the-top rock star excess, there was a clever reason for that requirement being included in the band’s contract with show promoters. In Van Halen’s case, the M&M’s® provided a quick indication of whether the show promoter had actually read the contract and therefore had read about the necessary infrastructure for the band’s immense stage show to run safely.

Much like the precision and attention to details required by the band and show promoters, in the case of motorcycle oil, engine specifications are different from automobile engines and will require necessary engine oil specifications to ensure that motorcycle engines run safely.

In the case of motorcycle oil, it is because motorcycle engines are so much different from car engines that they need commensurately different oil. Not only will automotive oil not protect a motorcycle engine as well, but it could even ruin the clutch and leave you stranded.

With all engine oil services, the first thing you'll notice is that the oil that comes out is black and pretty nasty looking in comparison to the golden liquid that comes in the bottle. “That means it is working,” assures Michael Warholic, Valvoline’s formulation scientist. “It is from the deposits being held in the oil by dispersants.”

This is a good time to take a close look and to make sure there aren’t any visible solid particles. Those would indicate a significant problem that you’ll need to have fixed before a catastrophic failure, he advised.

As long as you’re draining out the yucky black used-up oil and pouring fresh oil into the engine, why does it matter what kind of oil it is? All the good things you hear about the latest and greatest motor oils in television commercials makes them sound like they should be great in any application.

To start, you’ll want to consult your bike’s owner’s manual for the exact weight and grade recommended. “They may recommend a genuine [manufacturer-branded] oil, but it is really the specifications you need,” Warholic explained. The manual will also indicate the correct volume of oil to pour back into the engine. “Know how much oil the motor takes. You don’t want to over fill or under fill.”

But don’t stop there. Replacing the oil itself isn’t enough. Change the filter too, even though that job can be messy on bikes that don’t use automotive-style spin-on filters. “The filter takes a beating,” noted Warholic.

Probably the most significant challenge faced by motor oil used in motorcycle engines is heat. That is because many Harley-Davidson®, BMW® and Ducati® models are still air cooled, and Triumph retained air cooling until very recently.

Air cooling has the advantages of simplicity, light weight and clean appearance, with no clunky radiators and associated plumbing spoiling the motorcycle’s clean lines. However, air doesn’t whisk heat away from engines as efficiently as water does. 

Air-cooled engines not only run hotter in general, but they have local spots near the combustion chamber and exhaust port that get very hot, breaking down the oil and degrading its lubrication properties.


This is why motorcycle oil is specifically formulated to be more resistant to heat than automotive oil. “Those hot spots can be very detrimental to oil,” observed Warholic. “Trying to minimize the damage from that heat is very important.”

Another challenge for motorcycle oil is that most bikes, with the modern exception of Harley-Davidson’s® Big Twin models, have a unitized engine and transmission case. In such engines, the motor oil also lubricates the transmission. Those meshing gears can actually physically crunch the long petroleum molecules into shorter pieces, changing their properties in the process and reducing the oil’s ability to lubricate.

“Motorcycle oil has some unique parameters,” Warholic acknowledged. “You do tend to shear the oil and thin it. Motorcycle-specific oil provides better viscosity control over the life of the oil.”

Synthetic oils are especially strong standing up to both of these threats, so while Valvoline 4-Stroke Motorcycle Oil is a good choice, Valvoline 4-Stroke Full Synthetic Motorcycle Oil is a worthwhile insurance policy for added protection.

Additionally, most motorcycles employ a “wet clutch” in which the clutch assembly is bathed in engine oil, rather than an automotive-style “dry clutch,” which has no oil. Because the clutch’s job is to use friction to transfer power from the engine to the transmission and oil’s job is to be slippery, it is important that wet clutch motorcycles use oil formulated with this in mind, so they don’t make the clutch plates too slippery to function. Though, the first step in choosing an oil is to consult your bike’s owner’s manual for the exact weight and grade recommended.


“The problem with [automotive oil] in a motorcycle is that your clutch has to perform properly or else you get slippage during takeoff,” Warholic explained. “There is a certain friction test you have to pass and most [automotive] engine oils wouldn’t pass that.”

Another factor for motorcycle oil is the duty cycle of the typical motorcycle, which involves it spending a lot of time sitting around waiting for you to decide the weather is nice enough to finally go for a ride. This means that there is a lot of time for contaminants in the oil to congeal your bike’s lubricant into sludge. So motorcycle oil is formulated with these rest periods in mind.

“If it sits, it can get humidity in there,” Warholic warned. “Usually motorcycles are recreational so it sits, you run it, it sits, you run it.” That’s a very tough duty cycle for both the engine and its oil. “You can get a lot more water formation, sludge formation,” he said.

The good thing is that motorcycle-specific oil is getting better all the time. Synthetic oil already has an excellent base oil as its foundation, but even conventional oil’s base component is getting better, according to Warholic.

These changes mean, however, that if you have an older motorcycle, the exact specification recommended in your bike’s owner’s manual probably no longer exists. “The tie-back in specifications are harder to ascertain,” he cautioned. “Car oil is backward compatible, but in the transmission world and motorcycle world, that is not the case. It may not be easy to find the oil.”

Your bike maker should be able to provide guidance on the correct modern substitute. “You can call the manufacture to find out what they recommend. Or you can use the Valvoline hotline (1-800-TEAM-VAL). We have information for motorcycles that go back to the beginning of time.”

The motorcycle dealer or a local Valvoline retailer should also be able to help, too. “You could go to a local retailer selling that type of motorcycle” Warholic said. “You don’t want to guess, you don’t want to assume.”

When you’re done, pour the drain oil back into the empty bottles for the trip to the oil recycler. Often your local auto parts store (maybe where you bought your oil) and even many automotive quick-change shops like Valvoline Instant Oil Change will take your drain oil.

With that job done, you can ride without worry this summer, leaving you to focus your attention on solving the unsolved mystery of those green M&M’s®.

® Registered Trademark of third party.



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About the Contributor
Dan Carney
Jun 27, 2018

A member of the North American Car of the Year jury, Dan is Popular Science magazine's automotive editor, writing car reviews as well as auto industry analysis and commentary. He specializes in analyzing technical developments, particularly in the areas of motorsports, efficiency and safety. He has been published in The Wall Street Journal, The New York Times, Motor Trend, Popular Mechanics, and others.

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Tags: DIY




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