I have been using a 3 day acetone for at least 8 years, maybe longer and sometimes I have done it twice to the same stock when it did not come out oil free. I have never had the oil come back to the surface.
I would be concerned using ammonia unless there were some experience. Short soaks will only get the surface oil and dirt. To get deeper, you need to soak. I am not sure what that would do to the wood fibers. Might be worse than acetone.
I do know someone who does beautiful wood work who says the cheap oven cleaner at the dollar stores sprayed on the stock will work well. I assume it will only do surface oil and dirt. He also uses a simple green soak and says it works better than acetone.
YMMV
