Engine oil & filter

How it works

Engine oil lubricates and cools the moving parts: crankshaft, connecting rods, pistons, camshafts and, on most motorcycles, the gearbox and clutch too, which share the same oil. That is why a bike needs suitable oil: 4-stroke motorcycle oils carry the JASO MA or MA2 rating, designed so the wet clutch doesn't slip, whereas some 'energy-saving' car oils contain additives that make it slip. With mileage, oil picks up particles, oxidises and loses viscosity; the oil filter traps contaminants until it is saturated. Worn-out oil protects the engine less well and can make gear changes notchier. Too low a level makes the engine run hot and can light the oil-pressure warning; too high a level also causes trouble (foaming, leaks). The viscosity (for example 10W40) and the change interval are set by the manufacturer.

Maintenance tips

• ✓Check the level with the engine warm then stopped for a few minutes, bike upright (not on the side stand), at the sight glass or dipstick.
• ✓Use the viscosity and rating given in the manual (JASO MA/MA2 for a wet clutch).
• ✓Change the oil and filter at the manufacturer's interval, and at least once a year if you ride little.
• ✓Replace the drain-plug washer at every oil change and torque the plug so you don't strip the crankcase thread.
• ✓If the oil-pressure warning comes on while riding, stop the engine immediately and check the level.