A few points from this article below (well worth a read). I won't argue that urethane doesn't carry down oil because it does. I will argue with modern reactives that a single bowler in a three game set with urethane can carry down enough oil to affect these oil slurping reactives much at all (unless they are perhaps exactly on your line). I will also argue another bowler with an oiler can affect your shot a lot more than a urethane ball bowler will by drying out the end of the pattern near your breakpoint and causing dreaded over under.
"So, in an effort to resolve this issue once and for all, I decided to take a factual, logical, scientific approach to carrydown.
Fact #1: The USBC requires that a minimum of three units of oil be used from gutter to gutter for the entire length of the oil pattern.
Fact #2: We have all thrown, or seen others throw, shots that miss so far to the outside of the lane that we feared that they were going in the gutter, only to see them make a violent turn back toward the pins, often resulting in a strike.
Logical Conclusion #1: Three units of oil is not enough volume to affect modern reactive bowling balls.
With this in mind, I enlisted the gracious aid of Dennis Mathews, the Bowling Operations Manager at Red Rock Lanes in Las Vegas, as well as Head Mechanic Jeff Zawislak, who took a tape reading of the streaks of oil coming off of the end of the pattern following 24 games of league play.
Please note that at only one spot on the lane—the nine board on the right side—was there two units of oil present in the streak. Everywhere else on the lane, the streaks measured less than two units of oil, with most being less than one unit in volume.
Logical Conclusion #2: The volume of oil present in streaks of “carrydown†is insufficient to affect the motion of reactive resin balls during league play. In other words, carrydown is no longer a significant factor in modern bowling. "
(edit: please note plenty of those league players were throwing at least plastic if not urethane for spares).
https://www.bowlingthismonth.com/bowling-tips/the-dead-zone-revisited/https://www.bowlingthismonth.com/bowling-tips/el-dorado-and-el-diablo/