The lead-free gasoline was begun to distribute from February, 1975 in our country following to U. S. A. Two pump system was accepted with unleaded regular and leaded premium gasoline to prevent valve seat recessions of used cars until further notice. In this paper the need of lead-free gasoline for 1975 automobile emision legislation and some problems from this acceptance are discussed. The catalyzer deactivation by trace lead from the contaminations, motor octane number of high aromatic fuel and road octane reguirement increase, and the fnfluence of fuel composition on the exhaust emission are described and the future “ideal” fuel is considered.
