Abstract: A method of operating a compression ignition internal combustion engine which comprises supplying the engine with an aqueous ethanol fuel and lubricating the engine with a lubricating oil composition which mitigates problems of interaction between the oil composition and the fuel, the lubricating oil composition comprising a major amount of a base oil of lubricating viscosity and a minor amount of additives comprising one or more nitrogen-containing dispersant additives and one or more neutral or over-based, metal salt-containing detergent additives, the metal salt-containing detergent additives being present in the lubricating oil composition at a total metal salt concentration in the lubricating oil composition of greater than 0 and up to 1% by weight and the weight ratio of the total amount of nitrogen in the dispersant additives:the total amount of metal salt in the detergent additives being, at least 0.1:1.