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ARE MOTORCYCLE TRANSMISSIONS REALLY PROTECTED WITH REGULAR OILS

Learn about the aspects surrounding transmission protection for motorbikes.

Motorcycle transmission

The automotive industry has evolved at a rapid pace in the development of technical specifications for the different components that equip engines and auxiliary mechanisms. When engine lubrication for vehicles started to be regulated, it was developed under working groups in organisations such as API, ACEA and ILSAC. All of these included physico-chemical parameters and different test results that a product had to pass in order to be considered suitable. 

 

In addition to these regulations, which are referred as general specifications, in light and heavy duty vehicles has in the recent past and to this day been led by the manufacturers themselves, with technical requirements and even exclusive tests and trials for their own engines. On this basis, they issue technical specifications that respond to the most demanding requirements of their engines. In motorbikes and scooters, however, this has happened differently.

1. SPECIFIC MOTORCYCLE OIL REGULATIONS

In 1994, when there was still no ad-hoc regulation for motorbike lubricants, a Japanese sub-committee of the JAMA (Japan Automobile Manufacturers Association) began to study the effects of the use of passenger car oil in motorbikes, as had been done up to that time. Japan, at that time, was the technological home of the world's most advanced motorbike technology and a major exporter in the market. The problem of using such a passenger car oil in motorbikes with shared engine, transmission and clutch sump, as well as in scooters characterised by much more limited cooling, was assessed (see article “Differences in the lubrication of passenger cars and motorbikes” in FastScan). Two years later, the first Japanese and world-wide standard for motorbike oils was launched. This came under the umbrella of JASO (Japanese Automotive Standards Organization). Other markets quickly adopted the standard, and parallel alternatives emerged from organisations such as API, which moved forward at the same pace.

 

In this first development, friction suitability for wet clutches and oil quality for motorbikes and scooters were regulated. As the evolution of automotive oils advanced, the JASO motorbike standard was updated numerous times to raise the quality standards to the highest possible level. It also gradually included improvements in emission control and fuel economy. JASO established itself as the global specification.

 

This quality standard ensured that the oil used in a motorbike or scooter was perfectly adequate to protect the engine and also to allow correct operation of the wet clutch, which requires some friction to allow correct engagement of the discs. However, there was nothing specific for transmission care. It was not until 2006 that a minimum phosphorus requirement was added. But why phosphorus?

 

Phosphorus is an element widely used in anti-wear and extreme pressure additives. It is widely used, under different chemical molecules, in oils susceptible to breaking down the lubrication layer due to the mechanical stresses. This is common in transmissions. It typically generates a sacrificial film, where the energy generated by a mechanical impact is absorbed by the chemical transformation of this substance and thus protects the surfaces. JASO included a minimum phosphorus content in its specification, compatible with the range established in other organisations such as API or ACEA on which it is partially based, in order to ensure sufficient protection of the transmission.

 

Theoretically, this would perfectly regulate the specification for motorbike oils, and the three sensitive elements (engine, clutch and transmission) were covered by its proposal. To address the testing of commercial lubricants that would like to claim the JASO standard, the manufacturer has to declare and evaluate with JASO that his product first of all meets the requirements of one of the selected API, ILSAC or ACEA levels. This ensures (due to the variety of tests involved) engine protection. Once verified, there are a number of physico-chemical requirements to be assessed. The most relevant are HTHS viscosity (high temperature and high shear), shear stability (to check resistance to mechanical stress, with a test simulating the behavior using a nozzle) and the above-mentioned phosphorus level.

 

Subsequently, there is a third phase where the performance of the oil in a wet clutch is evaluated (in a specific JASO test). Depending on the test result, the oil falls into one of two JASO categories (MA, for oils suitable for motorbikes with wet clutches, or MB, for oils that are not, typically scooters). 

2. DO MOTORCYCLE OILS REALLY GET TESTED AGAINST TRANSMISSION PROTECTION?

If we stop to think carefully, there is control over the parameters for all the components of the bike, but really only the actual performance is verified for the engine (by the underlying API, ACEA and/or ILSAC tests) and the clutch (by JASO's own test). For the transmission, however, despite requiring a minimum phosphor value and measuring shear stability, there is no real performance test on an actual motorbike transmission. 

 

In the lubricant industry, there are several tests used broadly to evaluate the performance of transmission oils, most notably the FZG (Forschungsstelle für Zahnräder und Getreibebau, meaning Research Centre for Gears and Gear). This test uses two gears and subjects them to different loads and operating conditions, which become increasingly severe until the oil is no longer able to separate the teeth properly and the failure stage occurs. The more stages the lubricant can withstand without failure, the more protection it can provide in the operation of a transmission or gear. While JASO has repeatedly tried to incorporate this or other tests into its updates, there are problems of lack of inter-laboratory repeatability. Because of this, this and other tests have been rejected by the working groups and other options are still being evaluated for its inclusion in future revisions of JASO. 

 

However, FZG is still a good gauge of actual transmission gear performance. This is why some motorbike manufacturers require FZG testing of their genuine oils, including evaluation of wear, pitting and micropitting (material breakage due to fatigue, in general). In addition, reputable lubricant manufacturers with broad experience in motorbike oil formulation, who have collaborated with both JASO and the manufacturers, voluntarily include FZG testing when developing a new product, in order to establish some technical rigor.

3. THE IMPORTANCE OF CHOOSING RIGHT OILS FOR A COMPLETE TRANSMISSION PROTECTION

It is vitally important to select a motorbike oil, not only that it meets the JASO standard recommended by the manufacturer, but also that it is developed and produced by a company that goes beyond the applicable standards and invests in in-house testing developments that ensure maximum protection of all components, including the transmission. 

 

At Castrol we've been ensuring the protection of all motorbike components for decades, and have experience in scenarios ranging from everyday riding and commuting to the highest levels of competition and racing. This is where we innovate in the formulation and bring it to our Power1 motorbike range, including the latest advances to protect the drivetrain of our beloved two-wheelers.

right oil
right oil