Well, my LS430 car can do about 866 Miles when full at cruising speed (70 ofc) so it takes twelve and a half hours to drain the tanks at 2200 RPM. This leads me to believe at tick over RPM which is ~5x less it should last 5x as long so two and a half days.
NB: I only have a C in maths, don't understand cars, and am "an idiot"
Your Lexus idles at 440rpm? Is it broken?
