Please note this article was published in September 2012 and the facts and opinions expressed may no longer be valid.

Diverging lubrication requirements

Why passenger car oils are not suitable for use in motorcycles

Ryan Welton, Infineum EMEA Small Engine Marketing Manager, explains how the lubrication requirements of cars and bikes is diverging.

As passenger car lubricant formulations are geared up to deliver fuel economy improvements, their use in motorcycle engines is becoming increasingly inappropriate.

One of the biggest drivers for change in today’s passenger car lubricants industry is the quest for improved fuel economy. But, the motorcycle lubricants market is evolving a little differently; with the drivers for change being more dependent upon the demands of users from different geographic regions.

In developing economies like Asia motorcycles are mainly used for personal mobility, while in the mature markets of North America and Europe they are predominantly used for leisure purposes.

These diverging requirements mean that additive and lubricant suppliers need to develop fit for purpose solutions for these markets.

Two markets two challenges

In North America and Europe, the motorcycle population is aging, which means it is increasingly important for owners to ensure their engines are well maintained to prolong working life.

Consumers here look for lubricants that can deliver advanced engine protection and are keen to share information about what works in their bike –fuel economy is not top of their priority lists.

In Asia demand for new motorcycles is increasing; a trend that is driven by the very fundamental needs of personal mobility and improved fuel economy to save money is important to end users. It is essential that these machines stay reliably in service, which means consumers demand reliable but low cost lubricants.

Users are looking for higher quality oils that offer better engine protection and extended engine life.

Motorcycle oil marketers face two big challenges.

  • First, how to differentiate their oils from passenger car motor oils (PCMO)
  • Second, how to effectively communicate product quality to these disparate customer groups that may have only limited knowledge of API and JASO lubricant quality specifications.

Motorcycles need tailored lubricants

Four-stroke motorcycle oils (MCO) need to deliver a level of performance that passenger car lubricants are just not formulated to address – because motorcycle engines are very different from car engines.

Yes, they are both four-strokes that power wheeled vehicles and run on petroleum based fuels. But the differences far outweigh these similarities and the two should not be handled in the same way.

Diverging Lube Requirements Inline Motorcycle Image

Motorcycle engines run hotter and at faster revolutions per minute than car engines. And, because the sump of a motorcycle is much smaller, the oil cycles through the engine much more frequently.

This means motorcycle engines require a really robust oil. In addition, because in many cases the oil lubricates the engine, the gears and the clutch, it is essential that the oil offers good shear stability, gear protection, and friction performance.

As automotive OEMs demand lubricants optimised for fuel economy, there is growing concern that PCMOs are becoming increasingly unsuitable for motorcycle lubrication.

Three important jobs

A tailored MCO has three different but equally important jobs to do.

  1. Engine protection – Motorcycle lubricants must provide improved oxidation and thermal stability, enhanced lubricity performance and more effective deposit control. The oil must also offer sufficient wear protection while preventing the formation of deposits in the narrow oil ways. To deliver on all of these requirements the use of specialised additives is essential for total engine protection.
  2. Clutch protection – PCMOs containing friction modifiers can struggle to maintain grip between the clutch plates and rings, which the rider may feel as a loss of acceleration. Equally, if the friction is too high the clutch may snatch when engaged giving poor power take up, which can make the machine jerk as the clutch is let out. A specifically tailored oil overcomes these issues.
  3. Gear protection – The oil must be able to resist shear, minimise metal-to-metal contact and maintain load carrying capacity. PCMOs are not designed to offer gear protection simply because the engines and gearboxes in cars use their own specific oils. Today’s low viscosity PCMOs, designed to deliver improved fuel economy, may not offer sufficient protection to motorcycle gears, and may even have the potential to cause gear failures in motorcycles that continue to use them.

Diverging requirements

As the difference between PCMO and MCO specifications widens it is clear that one oil cannot continue to meet both sets of requirements.

We expect a gear pitting test to be included in the next JASO four-stroke lubricant specification revision, which is due in 2015. This will widen the specification gap still further and make it increasingly difficult for PCMO products to pass the motorcycle lubricant specification.

Oil marketers that have specifically tailored motorcycle oils in their portfolio will be at a distinct advantage.

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