A two stroke engine lubricates the piston, crank, and flywheel side bearing separately from the gearbox and clutch lubrication system. This is done by mixing a 2-stroke oil in with the gasoline.

As gasoline is drawn into crankcase, oil is deposited onto the various parts as well as being burnt in the combustion chamber (hence the famous 2-stroke blue haze). Older bikes had a much higher oil to gasoline ratio than the more recent bikes. Most Vespas made after 1980 and the Lambretta 75SL ' Cometa' have automatic oil metering devices with a separate oil tank. A mechanical system mixes the correct amount of gas and oil for the motor. Vespas with this feature can be identified by a conical sight glass which is visible just below the fuel tap lever.

Note: BE VERY CAREFUL. The wrong mixture can seriously affect your engine and can even result in a piston seizure. If you are unsure of what ratio your bike requires please find your model for the correct information. Older scooters usually take about 5% (20:1) - 6% (17:1) and newer scooters are usually 2% (50:1). I have also included 3% (32:1) because many tuned motors use this ratio.