Motorcycle oil: why the bike needs its own oil
Car oil in the motorcycle? On many machines not a good idea. We explain why the wet clutch co-determines the oil.
The JASO standardOne oil for engine, gearbox and clutch
On most motorcycles a single oil lubricates engine, gearbox and the wet clutch running in the oil bath all at once. That is exactly where the catch is: many modern car oils contain friction-reducing additives (friction modifiers) so the engine runs more economically.
In a car that is good. In a motorcycle that very smooth film can make the clutch slip. That is why the bike needs an oil approved for wet clutches.
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JASO: the standard for the motorcycle
- JASO MA / MA2: for machines with a wet clutch, provides enough friction so the clutch grips cleanly. The right choice for most motorcycles.
- JASO MB: friction-reduced, for scooters with a dry clutch or separate gearbox lubrication.
- 2-stroke , JASO FB/FC/FD: own classes for two-strokes, here the oil is burned along.
Which class your machine needs is in the manual. If in doubt, JASO MA2 is the safe choice for bikes with a wet clutch.
Said honestly
Some riders run car oil for years without trouble, especially with machines that have separate lubrication. You can’t recommend that across the board: as soon as a wet clutch is involved, the wrong oil risks clutch slip and expensive wear. The surcharge for a real motorcycle oil with JASO approval is small against clutch damage. We give you the facts, the decision stays with you.
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