Hi and welcome to the forum,
Is that a Grand Vista 250 ?
Where are you located ?
... you may want to add these to your signiture.
According to a GrandVista 250 owners manual (2009):
Replace gear oil at: 300, 3000 and every +4000 kilometers
In Miles: 186, 1860, 4400, 6800 miles
I have heard that it is a messy job without the proper tools due to the small opening that you are putting the oil in.
Use a Turkey baster or large syringe. WalMart sells a baster + syringe in the cooking section... pretty cheap.
Did you just get the scooter used ?
Scoot Safely,