Every 2,000 miles top up to correct level.

The gearbox is lubricated with oil of the same grade as that which is used for Summer lubrication of engine.

To fill, remove the filler and level plugs, see Fig. 36. Pour in a small quantity of oil through the filler plug hole until it commences to run out of the level plug hole with the machine standing upright.

Allow the oil to run until the flow ceases and refit both plugs. If oil will run out of the level plug hole with the machine standing upright it is an indication that there is too much oil in the gearbox.

Too high a level will not prove detrimental, as the excess oil will only be likely to run into the primary chain cover, where it can of course do no harm. It cannot cause the clutch to slip if the clutch is adjusted correctly.

After a new machine has covered 500 miles it is desirable to drain the gearbox. The drain plug is at the rear of the housing at the bottom. To remove any sediment that may have collected in the bottom of the gearbox it may be flushed out with clean petrol. This must all be allowed to drain away before refilling with oil.

Screw in the drain plug after the gearbox has been drained and re-fill with oil as described above.

In normal service the gearbox oil should be changed about every 5,000 miles. No other attention is necessary.

Heavy gear oil or grease will not find its way to the various bearings in a satisfactory manner, and may involve some part running dry with the consequent risk of seizure. For this reason therefore, such lubricants must not be used.