What does the gear oil do?

[RickWaza]

Stupid question time. So I follow all the instructions here and replace the gear oil every time I replace the engine oil. It's pretty easy, so why not? My question is, what does this oil do? The CVT doesn't use oil, does it? I read something about it being for the rear axle, but I don't see how that works. I feel like my take off power goes down about oil change time and gets better after the oil change, but that may be in my head.

Thanks for answering stupid questions.

[Meis]

the CVT pulleys, belt, drive face, and clutch are all open air inside the casing. the gear oil is for the actual gears that the CVT transmits power to. just like in any vehicles transmission, the oil needs to be replaced/flushed every so often.

[Dooglas]

However, it does not need to be changed anywhere near as often as the crankcase oil in the engine. No combustion products (or much else) here to foul the oil. My Vespa manual recommends changing the rear hub oil once every 12,000 miles (20,000 km). That is every second engine oil change per the Vespa maintenance schedule. I'd think every second oil change would be more than adequate for a Buddy or a Blur.

[viney266]

Agreed ^^^ I do the rear end (gear) oil every other oil change.

[paracer]

Although, as you said, it is easy to change. And, it uses about $1.50 in fluid. Feel free to change it as often as you like. It's not as though your gear oil can be too fresh.

As I recall from seeing pictures, there are three gear shafts in the gearbox. One connected to the clutch, one idler shaft, and one connected to the axel. The gear oil is what lubes them. As has been said, it doesn't see dissolved combustibles, doesn't get very dirty, and doesn't even get particularly hot.

For all these reasons, I just use a cheap bottle of auto parts store brand gear oil. Just make sure the viscosity is close to the spec.