NASCAR will start requiring teams to use nitrogen in the NASCAR-issued pit guns starting this weekend at Talladega.

The air wrenches are designed to be driven by nitrogen, but there were a few teams using gases other than nitrogen, likely looking to gain an advantage. Bob Pockrass, NASCAR

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How can using a different compressed  gas, like CO2, or even compressed air (regular atmosphere) change the results of how an impact gun tightens or loosens a lug nut?

Isn't the pressure the deciding factor? Not the atomic structure of the gas under pressure? Like, how could Argon do the job any different than Nitrogen?

Reading the article about it http://www.thedrive.com/accelerator/20389/nascar-mandates-nitrogen-powered-pit-guns it seems that most of the issue is really about the high tech guns that the best funded teams have been using, which get the job done faster... and Nascar decided that had to stop, now they all get the same impact guns, which may not be working if the last guys to use them, from whatever team had them issued, dropped them a lot.

Figure, if they damage an impact gun, it most likely will mean their competition has to deal with a broken impact, not them.

David Ragan, of the smaller Front Row Motorsports, believes the pit gun mandate has enabled his team to better compete with the higher-funded teams like Joe Gibbs Racing.

"Last year, there was no chance we could average in the top-10 or 12 in pit stops over a weekend, because our equipment was inferior compared to the Joe Gibbs Racing teams, maybe the Penske teams and Hendrick Motorsports teams, because they had special components, parts, and pieces in their air guns and maybe even jacks that allowed them to do it faster and more efficiently,” Ragan said in an interview with SiriusXM NASCAR Radio.