Was the 2008 financial crisis caused more by the US subprime mortgage lending or more by an international energy and oil pricing crisis?
It's worth differentiating between the financial crisis of 2007-2009, and the recession that began in December 2007.

The financial crisis was indeed caused by a run on wholesale funding that was precipitated by significant losses on real estate, both subprime and otherwise. As noted in the first link, stresses in wholesale funding first appeared in August 2007. At that time, oil prices (WTI) were still \$70-\$80/barrel. 

Losses to financial institutions during the crisis that can reasonably be linked to oil are limited, and the timing is all wrong, so it's not credible to suggest that the increase in oil prices would have led to a financial crisis absent the actual mechanism (run on wholesale funding, significant losses on real estate assets) by which the financial crisis occurred.

That said, it's certainly likely that oil prices contributed to the recession that began in December 2007, as documented by James Hamilton, though the severity of this recession was in large part due to the fact that there was a financial crisis:


  Recessions associated with financial crises have been more severe and
  longer lasting than recessions associated with other shocks.
  Recoveries from such recessions have been typically slower, associated
  with weak domestic demand and tight credit conditions.


Thus, oil prices are likely to have contributed to pushing the economy into recession, which may have worsened credit losses, fueling the stresses in the financial sector, but it's not credible to claim that they were a primary factor in causing the financial crisis, as compared to the structural vulnerabilities relating to wholesale funding and securitized assets.