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ADV Prepping10 Synthetic Oil Myths and Misconceptions Debunked

10 Synthetic Oil Myths and Misconceptions Debunked

Motul’s top oil guru answers all your burning questions.

Published on 09.13.2019

With many adventure bikes and dual sport motorcycles requiring synthetic motor oil these days, there are a lot of myths swirling around about what to use, or not to use. And let’s face it, synthetic oil isn’t cheap. So the more we can clarify the misconceptions, the more-informed decisions we’ll make about how to best use our hard earned cash. One thing is certain, we wouldn’t be enjoying the incredible performance of modern machines today if it weren’t for advancements in motor oil. 
We talked to Motul’s top oil guru, Joey Cabrera, to help separate fact from fiction and answer all of our burning questions about synthetic oil. As the National Technical Director, Joey’s job is to travel the country advising companies and consumers on the right oil to use for different applications. He’s also a rider with several bikes in the garage, so he’s familiar with the concerns of motorcyclists. Joey shares his thoughts below  on some of the common questions and misconceptions in the adventure motorcycling community.
Motul Synthetic Oil Dakar Rally Sponsor
Some synthetic oils have been proven to increase horsepower in some cases.

1.) If you change your conventional oil regularly, you don’t need synthetic

Joey Cabrera: There are many benefits to using synthetic motor oil that you won’t get from just regular oil changes. Synthetic oils protect engines better under heat conditions and flow better under extremely cold conditions. Not only will it make your engine run cooler but also smoother because of how synthetics are designed. Synthetics are known to withstand heat better and not breakdown at high temperatures or high loads. Certain Synthetic oils, like our racing product, have also proven to increase horsepower in some cases. 

In addition, you can expect longer drain intervals, a better detergent package to clean up impurities, smoother shifting, and improved overall levels of performance. Several of our synthetic oils include Esters as well, which offer extra protection for cold startups by leaving a fine film on all ferrous metal components to prevent premature wear of high-stressed parts like cam lobes.

Changing synthetic motor oil


2.) Never use synthetic oil to break in an engine

JC: This is true. It is typically better to break in an engine with conventional oil because it will allow the piston rings to seat faster. It’s not that you can’t use a synthetic to break in an engine, it is the fact that higher-quality synthetics are more slippery and the process to break in an engine takes longer. 

Most engine builders prefer using a conventional oil for the initial break-in, and use a conventional oil for the next 300-600 miles before switching to a synthetic. Motorcycle manufacturers are also likely to use conventional oil for the first fill in a new motorcycle engine and break in, even when synthetic is recommended. When the bike is returned to the dealer for its first service (oil change) after 600 miles, then the bike is filled with synthetic.

3.) Once you switch to synthetic, you can’t go back. And never mix!

JC: It is a myth that you cannot return to using conventional oil after using a synthetic. If this were true, then every oil company would need to have a disclaimer on the bottle giving a warning to the consumer. It’s perfectly safe to switch between or mix synthetic and conventional oil. In fact, there are many products on the market that are synthetic/conventional blends.

Synthetic blends are largely a cost versus benefit decision. A product like Motul 5100 is designed for the customer that uses his/her bike more for commuting and doesn’t want to pay the price of a full synthetic. It blends traditional mineral oil with more technologically advanced synthetic oil, so you get many of the advantages of improved additives and refinement. They are less expensive than a full synthetic motor oil while offering higher performance than a conventional oil.

4.) ‘Synthetic’ Motor Oil is artificially created oil that isn’t derived from petroleum

JC: Synthetic oil is a lubricant consisting of chemical compounds that are artificially made. The base material, however, is still overwhelmingly crude oil that is distilled and then modified physically and chemically. The actual synthesis process and composition of additives is generally a commercial trade secret and will vary among producers.

The word “synthetic” describes a process and not so much the material. For example, white sand is synthesized into glass, but glass is never called ‘synthetic glass.’ Synthetic oils are like designer oils. It all starts from crude but through different processes, we end up with different groups designed for different applications. 

synthetic oil made in a lab
The word “synthetic” describes a process and not so much the material.

There are five different groups of base stocks used in engine oils. Groups I and II  are mineral oils (i.e. conventional petroleum oil), while Group III, IV and V are synthetics. A Group III synthetic is more refined than mineral oil and typically hydrocracked (higher pressure and heat) to achieve a purer base oil. Group IV (PAO) is refined mineral oil that undergoes a special process called “synthesizing.” Generally speaking, Group IV performs better than Group III oils in handling heat, oxidation, low temperature start ups, and has a higher film strength and viscosity index (ability to flow). However, with today’s technology, some Group III oils perform as well as a Group IV.

Motul’s Synthetic Group V (Esters) oils are mostly made from vegetables, minerals and animal fatty acids. Esters are much more expensive because the ingredients are collected from nature, then get synthesized (which is a very expensive process). Group V Esters have all the advantages of a Group IV PAO, plus they can handle even higher temperatures. When Esters are burned, they leave far less coking deposits and are attracted to metal parts with an electro-chemical bond five times stronger than mineral oil. 

5.) If your motorcycle manufacturer recommends synthetic oil, it’s still ok to use conventional

JC: If the manufacturer recommends synthetic then you should use what the manufacturer recommends. Engineers design motors to run with the type of oil that meets the engine’s specific tolerances and characteristics.

Keep in mind high-quality oil isn’t just for maintenance, it’s also insurance. This is especially important for those who ride far away from civilization like adventure riders do. What if a rock hits your radiator or your water pump fails, or you lose oil from a cracked side cover in a fall off-road? What would you rather have in your engine – a conventional oil that burns up very quickly and carbonizes, or a synthetic oil that can handle higher running temperatures (325° F to 360° F)?

Deciding what motor oil to use.

Considering the high-performance engines and the type of riding, I would strongly advise using a full or semi-synthetic oil for most dual sport and adventure motorcycles.

6.) There’s really no difference between motorcycle and car engine oils

JC: Car oils contain friction modifiers and are formulated with a focus on reducing friction between moving parts in an effort to improve fuel economy and reduce emissions. Also, these oils contain detergent additives, whose ash content is relatively high. If used in motorcycle engines, these could result in the formation of deposits on the piston crowns as well as the valve train. Deposits can cause pressure build up, leading to perforation and burning of components. 

Motorcycles, on the other hand, use the same oil for both the engine and the gearbox. Motorcycle oils are therefore uniquely formulated to offer protection for engine components and the transmission gears. They need to be slippery enough to protect the engine, but not too slippery that they affect the wet clutch found in most motorcycles.

synthetic oil designed for diesel engines.
Car oils are designed for a completely different set of engineering requirements. You should always use oil made specifically for motorcycles. 

Motorcycle oils are designed to strike a good balance between clutch performance, and engine and transmission protection – something that is not considered in the manufacturing of car oils. When car oil is used in a motorcycle the clutch may not fully engage, leading to clutch slippage and power loss.  

To avoid issues, always use a motor oil designed for motorcycles with JASO rating (i.e. safe to use with a wet clutch). JASO ratings are MA, MA1 and MA2 with MA being the most slippery and MA2 offering the best clutch performance. There is also a JASO MB rating designed for automatic transmissions like those found in scooters (don’t use with a wet clutch). 

7.) Any synthetic oil with a JASO rating is always ok to use

JC: I often come across riders who use automotive based synthetic oil in their bikes in an effort to save money. A JASO rating alone isn’t enough to make it safe for use in a motorcycle engine. Car oils are designed for different types of engines with different engineering requirements. A motorcycle engine has smaller components, runs at different temperatures, has different tolerances, and its oil must work with the gearbox and clutch – so it is important to use an oil that was designed to work in the environment the engineers intended it for. 

Look for JASO MA2 rating.

Also, keep in mind that some oil manufacturers may claim a JASO rating on their product but aren’t certified by JASO. A JASO “certified” oil has undergone testing to be allowed to display the certificate on the bottle. Check the JASO website to see if the oil you are considering is listed as certified by JASO. 

8.) So you are low on oil in the middle of nowhere. Any oil will do…

JC: If you have limited options for oil in a remote area, first try to avoid using any oil that doesn’t have a JASO MA, MA1 or MA2 rating. There is no issue with mixing a conventional oil with synthetic, but try not to mix in higher viscosities than are recommended for your motorcycle. Whenever you have to mix in something non-optimal to get out of your current situation, make sure you change it the first chance you get with the proper oil for your bike.

motorcycle oil selection may be limited in remote areas.

9.) Using synthetic oil can cause oil leaks

JC: With modern motorcycles, you should not have any issues with oil leaks using synthetics. However, oil leaks may occur with older motorcycles that have a lot of miles. The problem isn’t the oil though. The powerful detergents in synthetic oil do an admirable job of cleaning out the crud within the engine. As it does this, it also locates the weak sections of your old gaskets and cleans the crud out that was previously preventing any oil from leaking out.

What’s the solution if you’ve made this mistake? Well, you can’t just change back to conventional oil, it’s going to leak through the old gaskets as well. You’ll have to replace the gaskets to fix the leak. If an old motorcycle engine has been rebuilt with quality gaskets, then there is no problem with using a synthetic or semi-synthetic. If it hasn’t, then it’s a good idea to stick with a conventional product.

10.) The best place to get advice about oil is to post a question on the forums

JC: Any time you post a question about oil in a forum or on social media, you are bound to get a lot of different opinions – many of which may not be the best advice. If you have questions about what oil to use for a specific application, we at Motul are always happy to share our expertise. You can contact us through the Motul website and your questions will be forwarded to either myself or one of our other oil techs.

Author: Rob Dabney

Rob Dabney started a lifelong obsession with motorcycles at the age of 15 when he purchased his first bike – a 1982 Honda MB5. Through his 20’s and 30’s he competed in off-road desert races, including the Baja 250, 500 and 1000. Eventually, his proclivity for exploration led him to dual sport and adventure riding. Rob’s never-ending quest to discover what’s around the next bend has taken him on Adventures in Mexico, North Africa, Europe, and throughout the American West. As a moto journalist, he enjoys inspiring others to seek adventure across horizons both near and far.

Author: Rob Dabney

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46 thoughts on “10 Synthetic Oil Myths and Misconceptions Debunked

    • Kawasaki doesn’t require synthetic oil for KLRs so nothing wrong with running conventional oil, especially if you ride easy and change more frequently. There are some reasonably priced synthetic blends you might consider too that offer a little extra protection for cold starts, high temps, etc. Just added insurance to help prevent failure, especially if you don’t know how well the previous owner maintained the bike. It’s a cost/benefit decision every rider has to make.

      • Rob;
        I ran 15/40 Rotella in my KLR for over 70,000 miles with no Issues.
        I did change it at 2 to 3,ooo mile intervals.
        Doing a oil sample I found that NOTHING lasted over 3,500 miles in that bike without severe shear / breakdown.
        It also was a oil burner from day one (08 model) so it was fill up the oil & check the gas every 300 or so miles.
        Such is life…..

  1. Good food for thought ! Old rule of thumb “grease & oil is cheap “ when it comes to any piece of machinery. Originally grease base consisted from a olive oil mineral oil (shale extraction) tallow (animal fat) soap base eventually mixed into a crude oil mixture. The technology has come a long way in 160 plus years. Valvoline being the first brand name oil product developed by a doctor following the American Civil War
    One area that should be considered when it comes to type/brand/grade of oil use as to the engine specifications is variants of ambient tepature changes and how it can effect cold starts. A engine using cartridge type filters, whether water cooled or equipped with a oil cooler should be allowed to warm to operating tempature at a moderate to low rpm and not the staggered erratic snapping of the throttle to avoid filter collapse. Synthetic mixes is engineered to compensate and safe guard in these situations.
    Although, prolong terms between changes can also cause similar problems. Variations in crankcase volumes can also determine change cycles before the oil viscosity values drop.
    A good read supporting Robs interview.

  2. I agree with most of the stuff here and the point of crazy opinions when you ask oil questions online .I’m just not sure taking everything an oil salesman says as fact . Would have been nice to hear from an engineer with less sales motivation .

      • Group III is a controversial class as they are derived from crude oil like Groups I and II, but their molecules have been so changed by severe processing that nowadays they are sold as Synthetics. Most people in the US now accept Group III as synthetic but the discussion remains heated among purists.

      • The law says group III is synthetic. Some lawsuit back in the 90’s against castrol syntec or something made it this way…….

    • As a mechanic with 18 years of experience working for factory race teams I can tell you he is correct. In fact not only hp but torque output.

  3. Any recommendations on air cooled 4 strokes? Would like to try a synthetic or semi syn on a XR650L. Just did a 300 mile loop going over two 12000 ft passes and oil temps reached 300 degrees at times using standard 10-40.

    No problems at all but temps were alarming – no oil cooler. Would a synthetic give better temp protection without clutch problems or should I stick with conventional oil and just add an oil cooler??

  4. Hello fellow riders and machinery operators —- 1st Question:– What is the best way to start an ARGUMENT? —–Start telling people what you know about oils. —– ANY BRAND ——Tell me ANOTHER thing Have you ever heard of an oil company being sued for a faulty OIL PRODUCT?———– The first SYNTHETIC OIL WAS MANUFACTURED by “MOBIL OIL”——- They call their motor oil “MOBIL ONE” —— What in laymen s terms is a synthetic oil ?——– it is TOTALLY MINERAL OIL that has BEEN SORTED OUT IN THE DIFFERENT SIZES OF EACH MOLECULES ———- Then they collect all the Molecules of one particulate size——- This is like the basic product —— The large oil refiners then sell this to the small retail oil retailers who THEN ADD THEIR SO CALLED MAGIC ADDITIVES!——————The BIG sales pitch of all SYNTHETIC OIL PRODUCERS IS SYN OILS REMOVES HEAT FROM THE ENGINE QUICKER ——- With the molecules being all the same size like ball bearings they can coat more of the inside surface of the engine and thus transfer the heat to the cooler surfaces of the engine ——– Now I am a retired 72 year old motorcycle mechanic —– I have a stable of 6 motorcycles my favorite being a Kawasaki Super SHERPA —- It is a 250cc de-tuned engine ,long travel suspension —-I have been places on this bike that is unbelievable —–especially for my age —– I give credit to the bike not my riding skills —– Now to the guts of the story —–One of my favorite rides on dirt is up and over a rain Forrest covered mountain ——-I usually attack it from the Western approach ———– From the bottom to the top it is very steep with huge deep narrow wash outs criss crossing each other ——- In three spots it levels out on small flat spots —— The Sherpa has std gearing 6 speed box ———- Engine warmed up standard oil pressure is by Kawasaki [BY MEMORY] 5 PSI AT ABOUT 2500 RPM——-From the bottom to the top of the mountain takes approx 15 minutes———- I put the transmission in 1st gear and that is where it has to stay stays because of the ruts and steep climb ——– Guess what HAPPENS regardless of what oil I USE AND ALSO i HAVE A LARGE OIL COOLER FITTED ———– The oil OVERHEATS & I SOON HAVE ZERO OIL PRESSURE ———- I THEN STOP ON EACH OF THE THREE FLAT AREAS AND
    No arguments ENTERED INTO as I ALREADY KNOW i WILL WIN and you will become angry and then yell nasty words to me ——— Cheers everybody Wes.

    • You came very close to almost the real reason but no cigar ………petroleum oil no two molecules same size,,so only the largest of still irregular in shape and size carry all the load …but 100% pure synthetic all hydrocarbon molecules are exactly the same size carrying more load all the time practically eliminating sll wear factors …. .and you will never see this info advertised nor will any research tell and admit to this absolute fact ..and you will never find this fact printed on any brand of a container of oil …and now they claim not to change out synthetic oil for 7000 up to the extended high mileage of 15,000 is all hype totally b.s. …when synthetic oil turns black all of its advantages are gone instantly as all hydrocarbon molecules will all break at the same time simply because they were all the same size so you cant hreak one without breaking all of them at the s
      the synthetic last almost twice as long ..which in my case about 1500 more miles …the best of the petroleum i was chanig every 2000 miles before it turned black at 3000 miles …and the synthetic i change at 3500 miles
      Mobile 1 passes testing of the highest abuses more than any other oil..but just because mobile 1 will withstand. Higher temps than any. other brand …never never allow oil temps to be higher than coolant temps …if you do any oil will glaze the cylinder walls and cause server blow by losing power and gas mileage …and checking the compression is no indication at all ..only a cylinder leak down test will show

  5. yes oil cooler use std oil as some friction modifiers will stuff the clutch friction plates & slip

    use an air cooled engine oil ——- heat destroys oil very quickly —-looks clean but won’t lubricate!

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  10. Thanks for the nice article. I’ve read most of that information before.Also thanks for the link to the JASO web site. This raises a couple of questions for me. First the MA ratings on the site are in conflict with those on the bottle of oil I have. Specifically Castrol Power 1 Full Synthetic 4T 10w-50. The label on the bottle says it’s MA2 but the JASO list says MA. Second question, how do you determine what group number an oil is? I can’t find any information on the bottle or the JASO site. Thanks again

  11. Hello Everyone it is Wes here. Just the other day I walked into my local bottle shop—— I am a beer drinker myself but being in my 70’s I have slowed down considerably —– Anyway for one period of my early years I lived in a huge GRAPE growing area —– KEEP WITH ME HERE — To harvest the grapes for wine they use a HUGE MECHANICAL harvester that has a thousand knives —- with the result a bloody lot more than grapes go into the crusher to get the grape juice —– rats birds nest lizards insects rats mice and on and on.—— not only that but the grapes in certain areas are harvested WELL before they are ripe and full of their sugars.—– REASON:– before the hail season —–after the crushing the liquids are filtered and tested to see what they have got to START WITH. ——– Once they know what they have got and what they have missing ——– The Chemist then get on the phone to the other wineries around the country ——- Next they fill a tanker truck with their juices and SWAP it WITH another winery 1000’s klm away —-The tanker returns home tanks full of the juices from the other area and this is mixed in with the juices from the first winery ——- When you buy a bottle of wine on the label it might say product of “WONDERFUL LAND” —— This is the first big LIE! —– It is a mixture of juices from the 4 corners of the country ——- Now the label itself —– The DESCRIPTION OF THE WINE ——-The claims that are made are out of this world —— To tell if a wine is good is to SIMPLY DRINK IT! ———- Here is something that may surprise you ! “I have often been told by wine drinkers that most times the “CHEAPEST WINES USUALLY ARE THE NICEST TO DRINK” ——- “Don’t quote me on that!” —– “OTHERS REMEMBER!”

    I think that the oil industry and the wine industry is very similar —-BOTH their labels are written by POETS ——-

    I am not having a go at anyone in particular but when you write something and put it on the NET it must be written in a way so the average LAY person can fully understand what you are saying ——- “EXAMPLE :– The oil handles the heat ? —— Does this mean the oil itself is not damaged by the heat?——- Or does it mean that the oil removes / transfer the heat being created in the engine / transmission.

    The first label you read on a beer is the PRICE LABEL.HA! HA! ha!

    Before I go —– I stated in my last post that MOBIL OIL CO produced the first fully synthetic oil — well another reader pointed out to me that another company was! —– I checked on the net and now the truth is that there are about 50 companies who were first so we were both wrong.

    I hope you enjoyed the wine industry tour Cheers everyone ! Still friends I trust.

    Cheers EVERYONE. Wes Mills.

    PS. I might now receive a legal letter from the WINE INDUSTRY! HA! ha! HA!

  12. Hello sir .. Which motul oil i use in my yamaha fzs v2. 0 (150cc) company recommended 20w40 but i want to switch to motul so please provide me some information

  13. The Motul 7100 is a fantastic oil which is recommended by KTM. Earlier they used to recommend the Motul 300V as well but then they removed that from the recommendation!
    I head from a KTM dealer that 300V caused leaks of some sort and that was the reason it was pulled.
    Contrary to this, there are a lot of people using the 300V for a long time. Those who use it swear by it being better than the 7100.
    But the 300V itself is a mysterious oil. The fact that there is “Racing Oil” stamped on it and no certifications printed on it makes us doubt whether it is compatible with street bikes.
    Also, a lot of mechanics and tuners say that the drain interval of the 300V is very short since it is a racing oil and is not meant to have long service interval.
    I have raised this question multiple times with Motul and never received a prompt answer.

  14. It makes ZERO sense to use ANY oil with a Winter rating in ANY engine that only gets used in hot weather.
    A straight weight oil is a MUCH better oil in every way and should ALWAYS be the choice for air cooled engines

    • Hi Dheeraj. I spoke to Joey the Motul technical director about this and he says the gaskets on some bikes from the mid-80s and earlier used paper or cork gaskets that can leak with an ultra-slippery full synthetic. Your 2000 model should not have this problem if it’s been well maintained. But if it has lived a hard life with a lot of miles, ridden hard or stored outside, a full synthetic has detergents that clean up all the sludge and may squeeze through some of the tiny cuts and pores in the old deteriorated gaskets. If that’s the case, your safest bet is to use a semi-synthetic like Motul 5100 that has many of the high-temp protection features of a full-synthetic that are key for air-cooled motors but you can use it without worrying about oil leaks. Hope that helps!

  15. Synthetic oils protect engines better under heat conditions and flow better under extremely cold conditions. Not only will it make your engine run cooler but also smoother because of how synthetics are designed.

  16. I have a question….. So I have a 2021 Honda Rebel 1100 and have had oil consumption problems. Did the 600 mile break in service and switched to amsoil. Hit 1200 miles and oil started to burn off and had blue smoke on cold starts. Took it to the dealer and they’re saying I switched to a full synthetic too early and it didn’t let the Valves seat fully so it’s causing it to leak. They switched me back to non synthetic to let everything “seal properly” and haven’t had oil burn off so far after 200 miles of riding so now they’re just saying the non synthetic fixed it. Can it actually be fixed just by switching oils or is it just a bandaid to a real problem? I do still notice some blue smoke on cold starts even after the oil change

    • Switching to synthetic after 600 miles is very common and should not be a problem. If it’s still having oil consumption issues, it might be worth getting a second opinion at a different location.

  17. Is it OK to top off or change brand of synthetic oil. I have a Kawasaki KLR and two quarts of Motul racing oil for my Ducati’s sitting around.

    • Sure you can top off or change the brand of synthetic oil, or mix in non-synthetic oil with synthetic oil. Just make sure it’s motorcycle oil and that you are using the recommended viscosity and you’ll be fine.

  18. I have a 1967 harley davidson golf cart. What would be the best 2 strok oil to mix with gas for it? reg or synthetic. It is the original engine it it.


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