Our 767-200ER's carry 23900 US Gallons, they are the last passenger versions built with the most powerful engines available.
Never came close to filling one up on even our longest routes (up to 12 hrs)
We had planned to use it on longer flights but it lacked a proper crew rest area.
The FAA insisted on bunks for anything over 12 and there really isn't room to put them inside a relatively small cabin economically.
It can go a long way
Full fuel and no load I have no doubt it could go at least 16 hours.
A lovely machine.