Does Synthetic Motorcycle Oil Cause Wet Clutch Problems?

We consult one of Canada’s top amateur road racers and the mechanic for two of the top amateur MXer’s in the nation.

Despite the fact that synthetic motorcycle oil has been on the market for more than a generation, some old-wives tales refuse to die. There are still riders that hold onto the belief that synthetic motorcycle oil can cause slippage or clutch plate glazing when used in transmissions with wet clutches. This claim was even repeated by the parts manager of a major OEM dealer to our colleague John Westendorp. This continues to be a head-shaker for us, because of all of the products we sell, AMSOIL motorcycle oils consistently earn the most frequent and vocal accolades from customers. After a decade in this business, how many complaints have we received about AMSOIL motorcycle oils causing clutch issues? Exactly zero.

We do have a theory on how this misconception took hold and why it continues to circulate. In the early days of synthetics, motorcycle riders may have used automotive synthetic engine oil in their transmissions looking to gain the benefits of a synthetic in their bikes. Unfortunately, automotive motor oils for gasoline service; both synthetic and conventional, contain friction modifiers. Friction modifiers are additives that literally reduce friction and improve fuel economy. All automotive engine oils for gasoline service are mandated to contain these. Simply put, friction modifiers are incompatible with motorcycle wet clutches. They will cause the clutch to slip under load and eventually glaze the clutch plates. Once this occurs, the only cure is a replacement of the clutch plates. Again this applies to both synthetic and conventional automotive engine oils for gasoline service. This canard seems to have stuck to synthetic motor oil because it is perceived to be “slipperier”. This error may still be happening to this day. Motorcycle oils (again both synthetic and conventional) do not contain friction modifiers.

But don’t take our word for it. Let’s talk to the people who take their bikes to the limit: the racers. Simply put, racing motorcycles are continually pushed to limits that street or trail-ridden bikes rarely (if ever) see. Let’s see if their clutches are withstanding this steady abuse with synthetic motorcycle oil in service. We consulted Canadian Superbike racer Marcel Irnie and Keith Biro of Biro Racing. While both are sponsored by AMSOIL, they are not paid spokesman, so we don’t see this as a conflict. Both drive thousands of kilometres to events across the continent and we can assure you that they would not risk a component failure because they are getting a good deal on oil.

First we talk to Keith Biro of Biro Racing. Keith is the chief mechanic and father of Kyle and Jarret Biro, two of the fastest amateur motocrossers in Canada. Kyle and Jarret have been terrorizing the Saskatchewan motocross scene for the past few years and have enjoyed tremendous success at the national level. While they may be small in stature, if you saw them sailing over double jumps and blasting through berms, you would understand why Biro Racing is the perfect subject for this article. There is no better person to consult than Keith Biro as he is one of the most fastidious race mechanics going. His bikes are maintained to a degree that would rival the practices of any factory team mechanic. If a stock part is not to his liking, it is replaced with an aftermarket upgrade. If a part is suspect or thought to be near the end of its useful

life, it is tossed in the dumpster with no second thoughts. Absolutely nothing is left to chance with Keith.

Biro Racing Bio

Hometown: Moose Jaw, SK

Riders: Kyle Biro (age 12), Jarret Biro (age 10). New to the scene is little brother, Kirk Biro (age 5), who started racing this year and hopes to follow in his brothers’ footsteps.

Business Manager: Tracy Biro

Current bikes:

• 2009 Cobra Junior 50cc LC (stock)
• 2006 KTM 65 (stock)
• 2008 KTM 65 (modified)
• 2010 Kawasaki KX85 (modified)
• 2010 Kawasaki KX85 (stock)
• 2011 Kawasaki KX100 (modified)

Major Accomplishments:

Kyle: 5-time Saskatchewan provincial champion, 2-time Western Canadian Champion, 2nd overall (top Canadian) 65cc 10-11yr class and 6th overall in 85cc 7-11 at 2010 Canadian Amateur Nationals at Walton, ON. Numerous wins and top-5 finishes across Western Canada and the Northern US.

Jarret: 2-time Saskatchewan provincial champion, 2010 Western Canadian 65cc 7-9 Champion, top-5 2010 Canadian Amateur Nationals 65cc 7-9yrs. Numerous wins and top-5 finishes across Western Canada and the Northern US.

Oildepot: Keith, there are still people who believe that synthetic motorcycle oil causes slippage in wet clutches. What is your view on this issue?

Keith Biro: There is absolutely no merit to this idea whatsoever. I can assure you that if synthetic oil even slightly elevated the risk of clutch failure, I wouldn’t touch the stuff. In fact, I’ll relate a story regarding Kyle’s 2008 KTM 65 that proves that the exact opposite is true. This bike has a highly modified engine that gets ridden to the max every minute it is in use. It makes significantly more power compared to a stock unit. I rebuilt this engine and clutch this past winter and we started fresh at zero engine hours with winter training in California this February. At exactly 15 engine hours, I again rebuilt the top end prior to racing a Loretta Lynn’s qualifier in Iowa at the end of April. I did not touch the clutch at this time. We have raced very aggressively this summer have we have had plenty of moisture and very heavy track conditions. In fact, some of the worst I’ve ever seen. Especially in Iowa, also Millville, MN and in Medicine Hat, AB where we had near rained-out conditions. We also had fairly hot conditions at the Western Canadian championships in July. With this in mind, prior to heading out to Walton, ON for the Canadian Amateur Nationals, I wanted to make sure that Kyle’s 65 was fresh again. I completed another top-end rebuild at 30.5 engine hours. Given the fact that KTM hydraulic clutches do not give warning of failure since they “self adjust” hydraulically instead of using a cable, I decided to change out the 30 hour clutch and put in new clutch fibre/steel/spring. I can tell you that the 30 hour clutch was in fantastic condition! When measured with callipers, the fibers and steels showed virtually no signs of wear and no discoloration. I kept it as a back-up as it is too good to throw away! I change gearcase oil every 1.5-2 engine hours with AMSOIL Synthetic 10W-40 Motorcycle Oil and again this bike is ridden to the absolute max.

Oildepot: As you talk to other mechanics in the pits, what role do you believe synthetic oil plays in today’s MX scene? Are conventional oils still being used by many racers?

Keith Biro: Many racers try cheaper transmission oils, only to realize that heat builds up very quickly and the result is accelerated clutch and gear wear. I still hear of the odd local racer buying the cheapest 20 liter pail of oil they can find and think that they are ahead by changing it almost every ride. However, even with fresh oil they are still getting transmission wear! Motocross racers using AMSOIL synthetic oils are able to get maximum power and durability out of the clutches and transmissions, especially in the high-heat/high-load conditions that typically exist in motocross!

Oildepot: You have been using AMSOIL synthetic oil in your bikes and vehicles for the last few years now. How have the products performed and what other performance benefits have you experienced?

Keith Biro: AMSOIL synthetic products have proven to be extremely reliable for our motocross team. We race all over North America under every racing condition you can imagine and our bikes have performed very consistently. From extreme heat to high and low altitude, our equipment performs flawlessly. Our transmissions, hydraulic and cable activated clutches have held up with only small amounts of wear which I consider normal in our scheduled maintenance program. Dominator Synthetic Two-Stroke Oil has always given us powerful and clean running engines under stock and modified set-ups. These products definitely give us a competitive edge. AMSOIL synthetic oil has also been incorporated into our tow vehicle maintenance schedule for the complete drive train. Reliability is extremely important as we tow a large trailer over 25,000KM during a racing season, with national round trips as far as 6000KM. I have been using Severe Gear 75W-90 Synthetic Gear Oil in front and rear limited slip differentials as well as AMSOIL Multi-Vehicle Synthetic ATF oil for Allison automatic transmission. “AME” 15W-40 and “DEO” 5W-40 Synthetic Diesel Engine Oil have been excellent in our Duramax. AMSOIL products give me great peace of mind travelling to and from competitions allowing our team to focus on racing! This oil had better be good because our 15,000lb trailer isn’t getting any lighter!

Marcel Irnie is widely known as one of Canada’s fastest amateur road racers. He is also well-known for his on-board videos and self-produced race documentaries. Marcel is colorful and at times even controversial, but there is no doubt that he is lightning fast and immensely talented. Marcel rode dirt bikes as a kid, but got the road racing bug after purchasing a new Suzuki GSXR 750 street bike in the spring of 2006. He took this stock bike to an open track day later that year and was immediately placed in the “licensed riders only” group. As he obviously possessed some natural talent, he started his racing career the next year. Within 3 seasons, he was national television standing on the podium at the Calgary round of the Part Canada Superbike Series. Marcel is a privateer in the classic sense of the term. He acts as his own mechanic, transport driver and business manager. Sleeping in a tent for weeks on end and fixing broken trailer axles at midnight is far from glamorous, but Irnie hopes that the hard work and sacrifice that he puts into his racing effort will pay off in a factory ride one day.

Marcel Irnie Bio

Hometown: Kelowna, BC

Current Bikes:

• Kawasaki zx6rr (2005)
• Kawasaki zx6r (2008)

 Major Accomplishments:

• 2nd Calgary Parts Canada National, 600 Amateur (2009 & 2010)
• 3rd Mosport Parts Canada National, 600 Amateur (2010)
• 3rd Oregon Motorcycle Road Racing Assoc., 600 Superbike (2010)
• 4th Washington Motorcycle Road Racing Assoc., 750 Superbike (2010)
• 4th Washington Motorcycle Road Racing Assoc., 750 Supersport (2010)

Oildepot: Marcel, hundreds of thousands of motorcyclists use synthetic oil in their motorcycles every year, yet there are still people who believe that synthetic motorcycle oil causes slippage in wet clutches. What is your view on this issue?

Marcel Irnie: I have been using AMSOIL 10W-40 and 10W-30 Motorcycle Oil in my race bikes for my entire racing career, with no clutch issues or slippage problems. Until recently, I had not changed a single clutch plate on both my bikes. Most professional racers change the clutch plates at least twice a year. I have never changed the clutch, or even examined the clutch in my 2005 race bike. It just started failing after 3 full superbike seasons and I purchased the bike used, so who knows how many hours were on this clutch. So I’m doing pretty well with around 120 races, and dozens of track days on the original stock clutches that came with my race bikes.

Oildepot: Had you been using synthetics prior to your racing career?

Marcel Irnie: No. I came to learn about AMSOIL after getting hit with some very expensive repairs. Just prior to my racing career, I purchased a brand new Suzuki GSXR 750 and rode this bike predominantly on the street. I was using Kawasaki and Suzuki-labelled mineral oil. In one season, I actually wrecked the transmission. The transmission would miss shifts like crazy and was always going into false neutrals. My mechanic said that the “transmission dog ears” had worn down. This ridiculous, excessive wear prompted me to seek out higher quality motorcycle oil and that lead me to AMSOIL products. It didn’t take me long to see that these products were the best and so 3 years ago I started an AMSOIL dealership and juggle this with my racing career.

Oildepot: You have been using AMSOIL synthetic oil in your bikes and vehicles for most of your career. You’ve even had lab analysis performed on used oil samples from your race bikes. How have the products performed and what performance benefits have you experienced?

Marcel Irnie: Oil analysis proves everything. I am able to extend my oil change intervals using AMSOIL Synthetics combined with oil analysis. The biggest problem faced by superbike motors is fuel dilution. When racing, we are often at full throttle which increases fuel dilution significantly. Fuel dilution is the only reason I must change my oil every 315 track minutes. When it reaches 5% dilution, the 10W-40 loses viscosity and essentially becomes a 10W-30. However, the oil’s additive package is still at 90%. Also, the oil is super clean with only 6ppm of silicone (dirt) after 315 race minutes. Aluminum wear levels are below 25ppm, which proves very low engine wear. The AMSOIL Nanofiber Ea Oil Filters keep my oil super clean. When I purchased my used 2008 superbike, the previous owner was running Silkolene Motorcycle Racing Oil and a stock oil filter. After one race weekend (around 250 minutes) oil analysis showed 55ppm silicon (dirt), and the wear metals were five times what I consistently observe using AMSOIL Synthetics. My motors last longer, I change my oil and filter less and my bike’s operating temperature stays lower. It’s win-win, all the way around.