Another important label on oil bottles is the JASO marking. This marking is essential as it signifies the suitability of which oil can be used for motorcycles with wet clutches or scooters. So please pay attention.
Who is JASO?
JASO is the acronym for Japanese Automotive Standards Organisation, who sets standards for the automotive industry in Japan, and is comparable to the Society of Automotive Engineers (SAE) in the United States.
What does JASO do?
However, JASO conducts tests on whether an engine oil is compatible with motorcycles' wet clutches (among other things) and is adopted as the worldwide standard.
Wet clutch vs. dry clutch
Historically, Japanese motorcycles were among - if not - the first the employ wet clutches. The engine oil is shared with the clutch and gearbox as opposed to a dry clutch where the clutch is in a separate case like in cars. Virtually all road-going motorcycles now use wet clutches. Pedigree race bikes like those in MotoGP, on the other hand, use dry clutches.
Since the clutch shares the same engine oil, it must not slip or at least has only a very small amount of slip despite the oil. As such, engine oils that are meant for motorcycles with wet clutches must allow the clutch and its friction plates to grip. And at the same time, the oil must not get sheared in between the gears in the gearbox. This is why motorcycle oils are more complex and more expensive than automotive (car) engine oils!
JASO MA, JASO MA2 - The standards for wet clutches
JASO introduced the JASO T 903:1998 clutch friction test and hence standard in 1998, specifically for wet clutches in four-stroke engines. The standard was revised in 2016 for even higher clutch friction index, hence the JASO T 903:2016 standard, and JASO MA2, commercially.
The standard is divided into two for the two types of power transmission.
JASO MA and MA2
A motorcycle engine oil with either one of these two certifications means it has the friction performance to prevent clutch slip. It therefore does not have friction modifiers (more on this later).
- JASO MA or MA2 certified oils are suitable for motorcycles with wet clutches.
- A JASO MA or MA2 oil CAN be used in scooters without a clutch system.
- It is also suitable for motorcycles with dry clutches.
An engine oil for scooters with automatic transmission that use CVT via belts. This oil can be mixed with friction modifiers for more fuel saving benefits, since they are not required to provided frictional properties for a clutch pack.
- A JASO MB oil CANNOT be used in motorcycles with wet clutches.
- It may be suitable for motorcycles with dry clutches, but check in the owners' manual or with the manufacturer on which type of oil, MA or MB.
- Certain scooters i.e. Honda X-ADV 750 and several others feature clutch systems such as motorcycles, but shift them automatically. Hence, these should be filled with JASO MA or MA2 oil. But again, check the owners' manual or manufacturer.
If your motorcycle has a clutch pack, use JASO MA or MA2 oil, and DO NOT use JASO MB oil. If your scooter does not have a clutch pack, use JASO MB oil (although you can use JASO MA/MA2 oil).
The JASO ratings are meant for motorcycle engines and their transmissions. This is why you should NOT use car engine oils in motorcycles.
We know there are certain HDEO (heavy duty engine oils) that are JASO rated. Our advice? Use at your own discretion.