The oil and oil business have a major role in world economy. Oil business started to grow on 1950'' and since then it has been the leading force in energy market. The OPEC Organisation of Petroleum Exporting Countries was founded on 1960 to annex the resources of oil producer countries. There are many market fundamentals, which affect on oil price and oil price formation. The major role is on the balance of supply and demand. Oil inventories and quantity of all oil reserves, deal made in oil exchange and political situations inclueding wars have also certain affect to the oil price. The oil markets were unstable during the last few years and the price curve of oil has been a real roller coaster. The situation has arrogated OPEC to act and be a charge in oil price formation. During the 1998 the price was on bottom price in years and vice versa on 2000 the price was excessively high. The OPEC has made a several decisions to stable the oil price fluctuation during these erratic years.