Via Barry Ritholtz:

Nothing has been a more reliable indicator for an upcoming recession as the price of Oil. Every major bear market, every major economic decline has been preceded by a large spike in oil prices. The 73-74 recession, recession of beginning 80’s and the recession of 2000. Oil prices jumped 80% between 1999 and 2000. Oil prices have been the most important indicator of major economic disasters. Whenever Oil prices rise about 80% from year ago levels, a fair chance does exist that a recession/bear market will follow.