Another question is whether the credit crunch will affect BP or ExxonMobile or Shell's oil production. Each of the US IOCs use a lot of subcontractors. These subcontractors can be highly leveraged. The gas stations can also be separately owned.

Some of the refiners are not IOCs. I found this news item:

Credit crunch may hit oil refinery output, trade

LONDON -- Liquidity problems in the global financial market may reduce oil product trade as refiners find it more difficult to obtain letters of credit and the number of trading counterparties falls, the IEA said on Friday.

With the letters of credit needed to facilitate exports subject to rising interest rates, refineries are finding it hard to maximise the value of their production, the Paris-based International Energy Agency said in its monthly oil market report.

"Counterparty risk is also limiting some trading companies' ability to deal with other companies, similarly resulting in reduced levels of trade," the report said.