How Long Does Fully Synthetic Engine Oil Last?
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Under sealed conditions, engine oil generally remains viable within a 5-year range, and fully synthetic oil also falls within this timeframe. However, once opened, the oil deteriorates more quickly and is best used within one year. Expired oil should not be used as its chemical composition may have altered, potentially harming the engine. Additional Information: Methods to Determine if Fully Synthetic Oil Has Deteriorated: 1. Fully synthetic oil should be a clear, semi-transparent, or transparent liquid. If oxidized, its color may change. Additionally, if the oil's transparency decreases, it has likely deteriorated. 2. If the oil emits a sour or foul odor, it has spoiled. If noticeable changes in viscosity (thinning or thickening) or uneven consistency are observed, it should no longer be used.