Sentence:  “We've seen a decrease in <WSD>oildowns</WSD> this year and we want to thank the teams for making that happen,” NHRA president Peter Clifford said. “<WSD>Oildowns</WSD> hurt our sport, and we realize no competitor wants to oil down the race track.  We have a commitment from teams to address the <WSD>oildown</WSD> situation and improve it.” 
Meaning of the word marked with <WSD> tags:  An oil spill sufficiently serious as to require the use of mechanical equipment to clean it up.