ALONG with bank runs and market crashes, oil shocks have rare power to set monsters loose. Starting with the Arab oil embargo of 1973, people have learnt that sudden surges in the price of oil cause economic havoc. Conversely, when the have because of a glut as in 1986, it has done the world a the price of oil cause of in power good. The rule of sudden thumb is slumps that a 10% fall in oil prices boosts growth by 0.1-0.5 percentage points.