My favorite, as mentioned, is Diesel Fuel or Kerosene, plastic or wood scrapers, then I paint on straight LESTOIL pine cleaner and rinse with hot (best) or cold water.
When I was a 17 I rebuilt the cast iron tranny in my '53 jeep. I used lestoil to clean it, there was absolutely NO oil residue left, the case began to lightly rust within hours. It's my FAVORITE degreaser, and it smells nice too!
John