No, it's not. Nitrogen is a larger molecule than Oxygen, so permeates through the rubber of the tire more slowly. The benefits are not worth the costs, however, so if you're paying for Nitrogen fill, you won't likely get your money back. The nice thing about Costco is that they fill for free, and will check your tire pressure and refill (or bring to proper pressure) whenever you bring it in - so long as you're willing to wait until there's a tech avail to do so. But then, who doesn't have sufficient time whilst shopping at Costco? I can spend hours in the place.