So in my effort to get a ball that handles oil well, I've seem to have purchased one of the most aggressive balls out right now: the Grudge.  I have the Thug Life, Rocket and Black Widow Limited Edition also.  I would like to  get something right under the Grudge, maybe a little let hook potential but can handle heavy oil.  The Grudge is great for more challenging patterns for me.  I would polish it but that's just going to let it get down lane a little smoother.  This ball has the ability to snap off the spot.  Aggressive but smoother.  That's what I'm looking for. 

If you would consider Ebonite products, check out the Track Paradox or the Ebonite Warrior Elite.  I have the Elite and it handles oil very well. 

The Ultimate Nirvana would be a great choice. When my Nirvana is starting to hook too much, I can switch to the Ultimate Nirvana which goes about 3-5 feet further down the lane but still has a strong snap at the backend.