Jay - i think you better get over to this page
download the PDF manauls for the QT50 and spend some time getting to know your Yamahopper.
As for the transmission, that PDF manual say .32 qt , that's 1/3 of one quart. Don't start by pouring a whole quart in there, of course you'll overflow the whole thing long before you get a whole quart in there.
Go get the manuals - read them - you're lucky to have them available free.