Sheila,
Some types of oil has a tendency to soften wood or so I've been told. Gun stock finishers use BLO ( boiled linseed oil) or Tru-Oil on the stocks. But it's made just for finishing wood.
I wouldn't use and don't use oil on my furniture. On the treadle I did the thread about I used the appropriate stain and then used shellac for the finish. After that I used Briwax polish to finish it off.
Joe