I cannot believe there are people actually calling for this. If you do that, yes it may be difficult to see where the change in units occur, but it is still taking away from the game. Part of bowling is finding where your ball works best, if you put coloring ing the oil that would make it far too easy. You would be able to see the carrydown, which is one of the more difficult obstacles to over come in bowling.
I am just saying, with many of the patterns out there now, and the equipment being so advanced the game is far easier than it was a while back.