The latest papers from Wikileaks show the US questioning Saudi claims about its oil reserves:
Saudi Aramco is having to run harder to stay in place - to replace the decline in existing production.
The Guardian also quotes former Saudi Aramco executive Sadad al-Husseini saying that Saudi Arabia's claims of 12.5 million barrels per day capacity is unachievable.
As with most Wikileaks cables, the information provided has been in the public domain for some time.