I think you can get two years with a double dose and starting with fresh fuel. May be best to ask Sta-Bil/Gold Eagle directly.

The tank could be drained at the hose connecting to the fuel pumps from the bottom of the tank. If it is a general overall refresh of the car that hose could be replaced anyway. Remember even when draining the tank fuel remains in the injectors, rail, pumps, filter and lines so use extra Sta-Bil either way.

Good luck!!!

__________________
"Rudeness is a weak man's imitation of strength" - Eric Hoffer