Would need more information is it the plastic reservior tank below seat you are referring too? This is for the transmission namely the tuff torq. It will depend on which model of tuff torq how much OIL it takes. There is model sticker on rear of axle means removing box and sweeper to see it. Tuff torq have website you can access the volume / reservior level of oil and what type needed. I have a countax c400h it has a k46e tuff torque fitted the reservior on it is half filled with oil when cold. I have changed oil on it isn't easy as no sump plug have to siphon it out or remove Axle to drain off.If you are changing oil must purge tranmission afterwards or it wont move, again tuff torq website have details on this too. Hope this has been some help
Rab, May 2020
