Scooter gear oil . ??????

Hi all . Ok as iv been cleaning my sons Peugeot speed fight 2 50cc air cooled . I found a small bolt at the back of the bike next to the back brake spring turns out is to top up the gear oil. Now the manual I have says that bikes after 2002 didn't need to top up the oil and done away with the bike bolt now my sons is a 57 reg so 2007/8 so it should be done away with . But anyway if there is oil.inside its 80..90. NOT HYPOID oil now what oil goes in there as I went to thunder road motorbikes and they only had hypoid oil and I went to halfords and in there car section had 80 90 oil NOT hypoid oil but synthetic and semi synthetic and this other stuff cant remember what it was called

So you guys who had Peugeot speed fight s what did you put in yours for gear oil . Thanks

Iv not tried to undo the bolt as I'm not sure what will happen if it all come squrtion out lol .

Any help will be fantastic ..

I can't imagine that it would be all that critical what goes in it to be honest . Wilkinson's ? It's not as if it's got a wet clutch , so anything that stops bits from wearing out by rubbing together should be fine .

The thing is prob supposed to be 80w90 but any oil is better than no oil, the first viscosity just means it's intended for cold ie w-winter, just put 90 in and tell him he can only ride it till it gets cold.

this is the rear final drive people

euro car parts 80/90

btw hypiod is just designed for having more pressure applied based on how the gears are cut