The question would be will they be able to exploit the oilfields in any real sense once the US cuts off trade with them. Oil refineries don't spring up overnight, not to mention the infrastructure to get the oil from the refineries to a port.
However, in order to have a freehand in the Far East, in particular to move towards the Dutch East Indies or Indochina, the Japanese simply can't avoid the problem of a semi-hostile US in the Philippines sitting across their lines of communications. As with Britain Japan can be easily strangled by a submarine blockade, which unless the Imperial Navy moves its operations to Manchuria, will face the same problems as in OTL.
I would also wonder about the impact of the refusal of the US to continue to sell them scrap metal, but consider this to be relatively minor.