Do you think those neanderthals had the technology to pull the oil out of the ground and build the processing plants to deliver the product around the world? Machines and equipment break down and need repairs/replacement... without these parts, the production would shut down. Seems to me that you could simply suggest that those parts would not be provided if...
The CIA supported the British government in toppling the Mossadegh government in Iran back in the 1950s for that very reason.
What kind of military did the Saudis have back in the 1950's? They were nothing but camel jockeys. Any resistance would have been crushed in hours. Hell, even on the 1970's when OPEC decided to boycott the US, they were nothing (in fact they are STILL nothing - how long did it take to defeat Iraq...the 4th biggest military at the time)
When OPEC decided to boycott the USA, the USA should have picked one country, invaded it, taken over the oil fields...and then ask what OPEC country wanted to be next.