The wood needs to be protected by a coating; oil really doesn't do enough for you. Of course, the secret to avoiding scratches is to eliminate sand & other abrasives from the floor which cause this underfoot. Use door mats & have everyone take their shoes off before walking inside. Also, chances are the 1st floor will scratch up more than the upper floors. One of the best ways to help conceal scratches (& all urethanes scratch with sand etc) is to use a low gloss coating - the lower the better. BonaKemi makes 2 superb products: Traffic & Mega. May need to have a specialist contractor apply these, depending on your comfort level with this kind of work.