Although Dean's claim to "only be gone a day" to help Benny might just mean "not very long" to Sam, driving from Oklahoma to Washington and back would require around 60 hours. Adding in time for sleep and actually helping Benny, it would be a minimum of 3 days.
The title card at the beginning of the episode clearly states the Winchesters are in Oregon, not Oklahoma. Oregon is right next Washington state.
The title card at the beginning of the episode clearly states the Winchesters are in Oregon, not Oklahoma. Oregon is right next Washington state.