| 摘要 |
PROBLEM TO BE SOLVED: To provide a deterioration determining device of engine oil capable of properly determining the replacing timing of the engine oil by accurately detecting deterioration in the engine oil. SOLUTION: Oil deterioration index maps (pentane dissoluble content maps A and B) are switched in response to the existence of an additive in the engine oil (Step ST22, ST23 and ST24) by using a phenomenon such that a characteristic of an oil deterioration index is largely changed compared with a state that, when in an additive existent state, on and after a residue of the additive is lost in the engine oil, when there is a correlation between an additive residual quantity in the engine oil and the oil deterioration index (for example, an increase quantity of a pentane indissoluble content per unit time). Thus, the replacing timing of the engine oil can be properly determined by enhancing oil deterioration detecting accuracy by switching the maps. COPYRIGHT: (C)2007,JPO&INPIT
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