Answer:
The first dramatic swing happened in the 1970s when there was a sharp rise in the real price of oil caused by the formation of OPEC.
In 1973, the World saw it's first oil spike when members of the Organization of Oil Exporting Countries (OPEC) being mostly Muslims, decided to punish the Western World for their perceived support of the Israelis in the Yom Kippur War. They placed an embargo on the sale of oil to the West and because they controlled 56% of the then World supply, this was enough to force the price of oil up due to the reduction in demand.
The second swing happened in the 2000s when there was a sharp rise in the real price of oil caused by increased demand from emerging economies.
From the early 2000s to 2008, the price of oil kept rising steadily till it reached around $147.30 in July 2008. This rise in prices was due to increased demand from newly industrialized and emerging nations like China that needed the oil to maintain their rapid growth.
The most recent swing happened in 2008 when there was a sharp drop in the real price of oil caused by a large financial crisis.
By December 2008, the price of oil had fallen to $32 and this was down to the global recession that was ravaging the World known as the Great Recession. As the world saw economic output fall, demand for oil decreased sharply thereby forcing the price of oil to fall dramatically.