We've recently moved into a new house with walnut work tops and would like some tips on caring for them! They are about 5 years old, so have some marks from the previous owners and I think that stuff put on them during our move has added scratches. We had laminate previously and always used pot stands to avoid burning them and dried off sink and surround after use due to living in a very hard water area, so am used to doing all of that. I am prepared to put work into looking after them but don't really know where to start - what is the best oil to use for example?