A gasoline composition is provided containing a hydrocarbon base fuel containing 5 to 20% v olefins, not greater than 5% v olefins of at least 10 carbon atoms, not greater than 5% v aromatics of at least 10 carbon atoms, initial boiling point in the range 24 to 45.degree. C., T.sub.10 in the range 38 to 60.degree. C., T.sub.50 in the range 77 to 110.degree. C., T.sub.90 in the range 130 to 190.degree. C. and final boiling point not greater than 220.degree. C. A method of operating an automobile using such gasoline composition as fuel is provided. Use of such gasoline composition as fuel provides improved stability of engine lubricant with reduced frequency of engine oil changes.