Reference balls

The world has a six month supply of oil. The Iranians if they close the Gulf must keep it closed for that period of time - a time when their own production is also lost.

Whether they could do so would be difficult, one not all production would be shut meaning the six month reserve would last longer. The US, Arab and European military response would be tremendous - the Iranians would definitely not be able to keep the straits closed for that long a period. The UAE would probably retake Abu Musa and the Thumbs.

Iranian oil production facilities would be destroyed

Probably NOT a good idea from the Iranian point of view