Gear oil

Gear oil is made to lubricate gearboxes and final drives. On most four-stroke motorcycles the engine and gearbox share the same oil, but separate gear oil is needed on:

• two-stroke motorcycles – the gearbox and clutch are separate from the engine;
• scooters – the rear reduction gearbox holds a small amount of oil (often 80W-90);
• shaft-drive bikes and ATV differentials – often need hypoid gear oil.

A gearbox with a wet clutch needs a motorcycle oil that won't make the clutch slip, while differentials and final drives may need a different (GL-4, GL-5) oil. Choose type and quantity from the service manual. Scooter gear oil is often forgotten – change it every few services.