On top of the pattern is most lanes have a urethane finish so the oil doesn't stay in one place. It moves around as it is bowled on so the shot can change. In the old days on lacquer finish, the pattern would move through use but not nearly as much because the lacquer was partially porous. There was an art to reading the oil or following the oil as preached by Nelson Burton Jr. I am a recovering Bowlaholic from which I quit cold turkey many years ago because of short oil. Now I am again a Poolaholic. :grin:
Al
Al