Abstract: A method for computing the quantity of injected fuel for an automobile engine equipped with an electronically controlled fuel injection system and an apparatus for detecting an exchange period for lubricating oils and constitutional parts are capable of informing a driver of an exchange period for an engine oil per use of a proper fuel quantity by calculating a total of the accumulated quantity of injected fuel for the automobile engine equipped with the electronically controlled fuel injection system. The method and apparatus are also capable of informing the driver of the exchange period for various lubricating oils and constitutional parts in accordance with the number of exchange of the engine oil and of allowing-the driver to exchange various lubricating oils and constitutional parts on a basis of accurate information under in an optimum condition. The method and apparatus also prevent the driver from being confused and extend the life span of the automobile engine.