Rocky Mountain Racway in Salt Lake City did this 7 or 8 years ago, it was a track rule. There was a ton of griping about it,they were fairly lenient with it at first, then they enforced it. I haven't raced there in 5 years since I moved east, but in all honesty it did make a difference in oildowns, and downtime at the track. I cant remember now if that rule was 11.99 or 10.99, but think it was 11.99. I bought a cheap one from Russler with the cutouts around the hole in the pan. Ive never needed mine luckily, but Ive seen them work, a big oildown that would take a long cleanup were gone. It was important there since RMR was very slow on any oildown. They didn't have the rule for street night if I remember correctly, but it was the rule and still is as far as I know.