[Sabreman]

Been there, done that!!

For the removing the gummy residue, DO NOT use acetone. Try paint thinner and if that doesn't work, then try laquer thinner. For the oil stain, and most other stains, use laundry detergent as a general cleaner, a scrub brush, and Ajax or Comet cleanser. They both have bleach and abrasives. I guarantee that they will work. The oil stain will mostly come out, but there may be a slight discoloration that the sun will take care of over time. Don't worry about abraiding the gelcoat too much - it needs abraiding if it's as dirty as you say. I've followed this recipe for 40 years and it works.

Use polishing compound and a wax after cleaning, if you like.