Petrol down to a dollar a litre may not be entirely welcome.While a deliberately low world oil price clearly benefits consumers (and transport costs), this is offset by its damage to Australia’s export income. In warning of the financial disruption brought about by the collapse of the mining boom’s record prices, especially for iron ore and coal, the headlines have had much less to say about the impact on Australia of its major resource crisis – the 75 per cent decimation of the price of oil.