Selling oil is irrelevant when a country is at war, or at the brink of a war.So where is Russia going to sell that oil? Russia is reliant on European markets for its income, just as many European states need Russian energy supplies - it would be at worst a temporary problem if it ever happened.
The oil is a weapon in Russian´s arsenal, and Europe needs the oil.
It don´think it matter, in that war, if Russia will suffer or not, because Europe is threatening with an economic war and Russia will retaliate in kind.
Russia will suffer, so will Europe.
Since Georgia started this war, and Europe want to gain this war in favour of Georgia, so Russia is calling the bluff to see until where NATO is willing to go, in my view.