WTI Oil (Cushing, OK) Spot Price (1986-2008)

Oil price has significant fat tails. So don't expect energy cost to be smooth. In fact, it is going to be a wide ride all the time.
It also has negative skewness like the Dow. High volatility causes oil price to go down!

Again, the first order fit (above) over-estimates the variance and the peak probability, which are corrected in the second order fit (below). This indicates oil price has observable volatility of volatility.