Try using Legends ball cleaner. It is SIGNIFICANTLY more effective than alcohol in removing oil as well as lane dirt. Plain household or isopropyl alcohol does remove oil.
As for ball oil extraction, it depends on many factors; there is no set numbers of games for any ball. Some of those factors are the roughness of the surface, the amount of revs the bowler throws, the roughness of the lane surface on which it is used, the amount of oil on which it is used, how much you wipe it off between throws, how well you clean after each use (legends cleaner vs alcohol), how quickly you clean it after each use (at home afterwards vs before you put it back in the bag at the center).
Some balls do absorb oil faster than others.
Your best basis is watching the reduction of performance of the ball as you use it. The degree to which it hooks less and less and hits weaker and weaker, and goes longer and longer ON THE SAME OIL PATTERN, THROWN BY THE SAME BOWLER!
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"None are so blind as those who will not see."
