One of the easiest ways to get oil out is to not let lane conditioner (oil) get in. I'm a big fan of wiping the ball off before every shot. Microfiber towels help remove oil from the surface actively as you bowl. By keeping the surface clean, you don't get oil, all ready on the ball from the last shot, effecting ball reaction.
The Ebonite company doesn't sanction any heating of the covers of their bowling balls (as in sun, oven, halogen spotlights, etc.) as a solution to oil absorption and reaction loss. But during a Visit a few National Tournaments ago to Las Vegas, bowling balls in the trunk of a rental car swaddled in Buff-a-Bags did have a tendancey to sweat oil in the 110 degree plus midday sun. But if you live in Vegas/Phoenix/the Dessert you all ready knew this. But Ebonite does have a system (called Hook Again) using dry chemicals to draw oil and unfortunately some of the plasticizers out of a bowling ball.
If you remove lane conditioner actively (while you bowl) and immediately after you complete your games, it has less time to soak in.
Warming the surface has some merit.
Plain rubbing alcohol (70 to 90 percent, high percentages are not any more effective, but can be diluted with water) will help clean the ball (it's what we use by the gallon in the store, and I suspect it's an ingredient in several ball cleaning products). Anything added (fragrance, color) will leave a residue, which can lead to other problems. So, not any alcohol based solvent cleaner will do.
Controlling the heat source is the key to addressing the oil in the ball problem. Ebonite will tell you, hot tap water (usually 120 degrees or so, hotter is not better) will warm the surface and float the oil off the ball. You must soak the ball (submerge it in a bucket or container) for half an hour. Still oily, they suggest do it again. Dealing with slimy grips and soggy tape is a downside. Let the ball COMPLETELY dry, don't hurry the drying process, or rush to use the ball.