As I can recall from Futurama season 06 episode 13, In the robonica spirit, the female bots had to wrestle in petroleum oil which got extinct, leaving bender with only a can of it. Bender, along with crew, goes down the earth,digging, to get more petrol. The ship gets wrecked due to pressure and there, 500 million years later, the crew gets converted into petrol.
When he got back into Planet Express office (where the two female bots were fighting), he sees enough petroleum oil already there (which wasn't when he left 500 million years back) and quoted
"There was enough petroleum for four and a half week, but it lasted for 500 million years. Its a miracle"
How did this petroleum arrived suddenly? If it was the same petrol which he used 500 million years back(amount to only few liters), how did it suddenly became a tub full of it? Also, isn't petrol a volatile liquid, which should've vanished into the air?