After a LOT of miscommunication, and a resort to pictures from the Quaker Oats site, the "foreign goods store" at Samick Shopping is carrying whole-flake Quaker Oats. (not Quick or Instant).. (if you don't know the differences, go to: http://www.quakeroatmeal.com/)
Large boxes are 10,000, small are 5,000. There is plenty of stock at the moment, and if enough people take the time to buy now, then supply will be assured for the future. ( so make lots of cookies! And, its a great cold-weather breakfast.)
Take the subway to Namchon, exit #1. Walk straight ahead to the corner and turn right onto the broad street. This road meanders over the top of Samick Hill and down the other side. Samick Shopping is on the other side of the hill, at the intersection with the stop light. (MegaMart to Kwanganli beach road) It is across from the Samick Beach apartments.
The "foreign goods store" is a tiny store outside the main supermarket. They open at 8 AM. Their phone number is: 623-7555
There is no degradation in quality if you store it in a sealed "Lock Lock" container. It will stay fresh for a year.