If you have slower ball speed, the Unleashed could be an oil ball for you. I say "COULD" because it is still a question. With the Phenom or Animal, there is no question that either will work on oil. I have now used my Animal 12 games, and like it more and more after every game. My local city tournament was this weekend, and the ball just about paid for itself. If the bowler alongside of the ball would have used his brain a little sooner, it would have paid for itself over 3 times.
With the box surfaces...the Phenom is a better oil ball than the Animal. My next ball purchase is an Animal to take the shine off of.
My dad has slower ball speed (roughly 14mph), he does not have a ton of hand, I would say below average actually, but he is behind the ball at his release, and his Phenom is almost unusable unless there is an absolute flood. His Unleashed is what he uses on oil. It gets length and has a 1500 polished finish it as well. If it was dulled down some he could probably use it in the heavy stuff too.