How to Determine if Car Engine Oil Has Deteriorated?
2 Answers
Methods to determine if car engine oil has deteriorated: 1. Check the color: Normal engine oil should be yellowish-brown and semi-transparent. Once water enters, it turns brown. After running for a while, the oil will gradually become milky white and produce some foam. As the oil is used for an extended period, it will carry sludge and metal shavings, turning black. When the oil becomes a shiny black color, it indicates that it needs to be replaced. 2. Method of observing the color: When checking the oil color, do so under sunlight or in a well-lit area. You can use a dedicated inspection stick or the oil dipstick to dip a small amount of oil and observe it against the light. If no metal shavings are visible in the oil, it can continue to be used. If there are excessive impurities like metal shavings, the oil has deteriorated and should no longer be used. 3. Smell the odor: Normal engine oil has a mild, slightly aromatic smell. If the oil emits a particularly pungent odor, it has deteriorated, and you should carefully inspect whether it needs immediate replacement.
After driving for over a decade, I've concluded there are three key indicators of degraded engine oil. When you pull out the dipstick and wipe it clean, if the color changes from golden to dark brown or ink-black, it's 80% degraded. Fresh oil feels as smooth as honey, but degraded oil becomes sticky or develops fine particles that feel gritty when rubbed. A burnt or sour smell is another sure sign. At every maintenance, I remind myself: check every 4,000-5,000 km for mostly city driving, or 7,000-8,000 km for highway-heavy use. Last time I delayed the change, the engine rattled like a tractor – the costly repair wasn't worth it. Now I make it a habit to check the dipstick monthly, saving both hassle and money.
