costello tonight. >> reporter: it's the largest release ever from the u.s. strategic patroleum reserve. 50 million barrels. but that's roughly the equivalent of what americans go through every 2 1/2 days. the spr is normally reserved for emergenies like wars or hurricanes that disrupt the national supply. this is the first release for a non-emergency. the u.s. partnering with india, japan, south korea, the united kingdom, and china to also release more oil. hoping to force opec to pump more to meet demand. critics say a move of this size is unlikely to help oil and gas prices in the long term.