How to change the gear box oil in a Vespa ET4 scooter

How to change the gear box oil in a Vespa ET4 scooter

Keep your scooter gears shifting smoothly

Changing the gear box oil, otherwise known as hub oil, is an important maintenance item on a Vespa ET4. According to the Vespa ET4 Owner’s Manual it should be changed every two years or 3000 miles.

The gear box oil on a scooter is the equivalent of transmission fluid on a car. The gear oil coats the gears of the scooter tranmisson while the engine is running. The gears and bearings of a scooter rely on the gear oil to reduce the stress they experience.

Gear box oil breaks down over time and useage. If not changed, it will turn into a thick dark molasses-like gunk. Eventually, the gears and bearings could seize resulting in a nasty crash. Changing the gear oil is fairly simple on a Vespa ET4 and can be accomplished in under an hour.


Step 1

Purchase gear box oil

Buy a quality fully synthetic SAE 80W/90 gear oil that meets API GL3 specifications or higher. You’ll only need 100cc of oil so one bottle will provide enough oil for several gear box oil changes.

Step 2

Park the scooter

Spread out the newspaper on a stable level surface. Park the scooter on top of the newspaper using the scooters center stand.

Step 3

Assemble the tools

Assemble the tools so that they will be within an easy arm reach.

Step 4

Loosen the gear box oil dipstick

Loosen the gear box oil dipstick (fill hole) on the left side of the scooter engine.

The oil dipstick/fill is the blue knob in the picture.

Step 5

Find the gear box oil drain plug

The gear box oil drain plug is located on the lower left left side of the scooter engine next to the rear wheel. From the right side of the Vespa ET4 look through rear wheel. Slowly turn the rear wheel until you spot the gear oil drain plug.

Step 6

Insert allen wrench

Put the allen wrench into the gear box drain plug. It should fit snuggly into the hole. Alternatively one can use a ratchet wrench with a 6 inch extension and a 6mm adaptor.

Step 7

Insert gear oil capture system

Slide the funnel through the rear wheel so that one end sits directly underneath the gear oil drain plug while the other end directs the oil into the oil pan.

Step 8

Loosen gear box drain plug

Loosen the gear box drain plug by turning the allen wrench counter-clockwise until the drain plug comes out. Let the oil drain out completely. It may take several minutes for it to drain. Remove the drain funnel.

Step 9

Install the gear oil drain plug

Remove the old brass crush washer from the drain plug or from the side of the engine. Clean the drain plug and install the new brass crush washer on it. Reinstall the gear oil drain plug. Tighten to a torque of 12.5 ft lbs.

Step 10

Add new gear box oil

Remove the gear box dipstick/fill hole. Use a large syringe or squeeze bottle to add the gear box oil through the fill hole. Wipe the dipstick clean and screw it into completely into place. Unscrew the dipstick and check that the gear oil reaches the MIN level on the dipstick. Screw the dipstick back into place. Take the used oil to a recycling facility.

Things Needed
• 6mm Allen wrench
• soda bottle split in half lengthwise
• 100cc SAE 80W/90 API GL3 gear box oil
• new brass crush washer for oil drain plug
• Squeeze bottle for oil
• pan for oil
• newspaper
• paper towels
• hand cleaner

Tips & Warnings
• Do not overfill your gear box with oil. Carefully measure the required amount of oil.
• Changing the gear box oil is much easier than changing the engine oil on a Vespa ET4.
• Change the gear box oil at least every other year.
• This guide is for the Vespa ET4 150cc Leader engine. The ET4 50cc and 125cc have different configurations.


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