That's right. Some mopeds have oil in the gearbox. The oil gets dirty pretty fast, especially if your moped motor has performance parts on it. Change it often. In this instructable, I am changing the oil on a 1978 Puch Maxi, with an E50 motor on it.
I made it at Techshop. They have a work bay where you can work on your car, motorcycle, moped... whatever! There are 3 of them around the SF Bay Area, so it's pretty convenient. There's others around the country and they have lots of tools and workshops. Wood, Metal, Fabrics, Electronics and more. It's rad.
Check it out here: www.techshop.ws