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Yamahas own-brand of motorcycle engine oil

Motorcycle Oils are a range of lubricants, including engine oils, which are specifically developed and marketed for use in the internal combustion engines and transmissions of motorcycles and may also be recommended for use in vehicles utilizing drive-trains similar to those of motorcycles, such as quad-bikes.


Motorcycle Engine Oil

The vast majority of modern motorcycles use the same oil to lubricate the engine, transmission, and (with the exception of bikes with dry clutches, such as Ducatis and some BMWs) the clutch. Normal, "car-derived" motor oils are designed just for engines, but were historically suitable in motorcycles. However, some of the latest American Petroleum Institute, or API specifications are completely unsuitable for motorcycles with wet clutches. Representative organisations of motorcycle manufactures, particularly Japanese Automotive Standards Organization, or JASO, work with lubricants manufacturers to create "motorcycle-specific" standards for oils, and the relevant oil companies then develop and test oils which are specifically made for motorcycles and in return, they have two different products with the same chemical content.

Transmission lubrication

Motorcycle transmissions, just like all gear-based automotive transmissions can quickly degrade a multi-viscosity, or multi-grade engine oil. Conventional car and truck transmission oils have specific EP, and other specialised anti-wear additives, but these EP additives are not suitable for the combined application of lubricating the engine and transmission with the same oil, as is the norm in motorcycles.

Multi-viscosity oils contain viscosity improver chemicals known as VIs that keep the oil from becoming too thin at high temperatures. The VIs are large chemicals that tend to shear between the cogs of a motorcycle transmission. That can have the effect of reducing a 10W-40 oil to a 10W-30 in a relatively short number of miles.

One solution to shearing is to use single weight oils, which do not have VIs and aren't susceptible to degradation in the transmission. However, single weight oils do not flow well in cold conditions, reducing overall lubrication until the oil has warmed up. An alternative is to use a synthetic oil. Synthetic oil are designed to have good cold-flow properties yet maintain high viscosity with fewer VIs.

Clutch lubrication

Energy Conserving (EC) oil can cause wet clutches to slip.

With the exception of most Ducatis, Moto Guzzis and BMWs, most motorcycles have a wet clutch. In a wet clutch, the clutch plates are immersed in oil. Some oils make the friction plates in the clutch slippery so that the clutch doesn't engage properly when shifting gears, or the clutch slips when the engine exceeds a certain torque. Some oils contain friction reducing chemicals. These oils are unsuitable for motorcycles. All 5W20 and 10W30 non-motorcycle engine oils have these friction reducers. Oils with an operating weight of 40 or greater are not required to have friction reducers. These oils are unlikely to cause clutch slippage.

One element of the JASO-MA standard is a friction test designed to determine suitability for wet clutch usage. An oil that meets JASO-MA is considered appropriate for wet clutch operations. Oils marketed as motorcycle-specific will carry the JASO-MA label. Other oils, such as Shell Rotella T heavy duty engine oil (HDEO) carry the JASO-MA certification.

A properly specified motorcycle oil will still allow for the appropriate lubrication and cooling of a motorcycle clutch, whilst maintaining 100% of the drive to be transmitted by the clutch, even under arduous operating conditions.

Cooling properties

Some motorcycles are air cooled, and rely solely on the oil to carry heat away from the engine. Synthetic oils are much better than conventional oils at cooling. Conventional oils are made of a mixture of different length hydrocarbons. Inside a pipe, the longer hydrocarbon molecules stay near the wall of the pipe and travel slowly while the shorter hydrocarbons quickly move through the center of the pipe. The long hydrocarbons are along the wall and pick up the majority of the heat from the engine and are unable to quickly distribute that heat to the cooling fins. Synthetic oil molecules are all the same size. Synthetic oil travels down a pipe uniformly and can transmit heat much more quickly than conventional oil. An air cooled engine lubricated by synthetic oil operates at a lower temperature than one cooled by conventional oil.




Up to date as of January 23, 2010

From Wikibooks, the open-content textbooks collection

Can Automotive Engine Oil Be Used?

Motorcycle oil is relatively expensive compared to automotive engine oil so it's been a long standing question if regular automotive engine oil can be used. The companies that make motorcycle specific engine oils state that their products contains special additives and formulated specifically for a motorcycle. However they never offer any independent test results to substantiate their claims.

Many[1][2] have actually been using automotive engine oil in their motorcycles for years. The key thing to watch out for is to make sure that if you have a wet clutch to make sure the oil is not labeled "energy conserving" (low friction) as they could cause clutch slippage (generally any oil rated 10W-40 or heavier is not, and any that is "energy conserving" should be labeled as part of the API).

Shell advices[3] that some diesel engine oils have properties that makes them well suited to be used also in motorcycle engines.

Some popular major producers of motor oil

  • American Refining Group, Inc.
  • Castrol
  • Fuchs Silkolene
  • Mobil 1
  • Motul
  • Pentosin
  • Royal Dutch Shell



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