Mostly agree, though there is the small valve connected to national reserves that can and has been turned on before. There's only so much a president can drain from the reserves though. I don't know what the maximum price effect that it can have time-wise is, but I would suspect not more than a year or so, and that would still be tied to market forces. I can't remember how big an effect it had when the last Bush did it.
Also, I think the strategic reserve valve only turns one way, to artificially reduce prices in a high market.
More than a YEAR?
BBBBBBBBBBBBBWWWWWWWWWWWWWWHAHAHAhahahahahahahahahahah!
The last two releases from the reserve were in 2005 (Hurricane Katrina supply domestic pumping interruption) and 2011 (disruptions caused by the Arab Spring movement, and matched by a similar release by IEA nations).
In both cases the price of oil was trending sharply higher. The releases only slowed the upward spiral, and only for less than a week, if that.
The reality is that a release from the SPR will do nothing to contain oil when it's in a climb mode being fueled by level production and rising demand.