My parents recently purchased a 1930's era buffet table like thing and it needs a little cleaning up. It looks like whoever owned it previously didn't clean it very well and there are a few spots that may be a little hard to get up. My mother is obsessed with finding a good way to clean it that will preserve it [I want it when all is said and done, so I'd prefer it that way as well] but still make it look amazing. Any ideas? She's seen to use Murphy's soap and not to use it. To use lemon oil, and not to use it. What should we do?