Maybe our fine President *knows* there will be a problem with oil supply in the near future...

Like when we invade Iran?

In which case the reserve would probably be used to make fuel for military vehicles and aircraft. In the event of an attack on Iran, fuel shortages would last a lot longer then 90 days, and the US military is one of the world's largest users of oil...during WWII, people didn't drive unless they got the right permit...everyone else walked or took a bus.