What are the common methods to identify if engine oil has deteriorated?
2 Answers
Methods to identify if engine oil has deteriorated: 1. Smell the odor - deteriorated engine oil usually has a very obvious sour and foul smell. If such odor is detected, the oil should be replaced promptly; 2. High-quality engine oil has excellent tactile properties - it's lubricious, contains minimal wear debris, and feels frictionless. If impurities are present, the oil will feel sticky or even gritty when rubbed between fingers; 3. Color identification method - the condition of engine oil can also be determined by observing its color. Place a few drops of used oil on paper. After the oil permeates, good quality oil leaves no powder residue, feels dry and smooth to touch, and shows clear yellow infiltration rings. If the color appears dark brownish-black, it indicates the presence of impurities.
Having driven for decades, I've found that oil degradation is a common issue. The simplest method is to observe the oil color: fresh oil is as clear as honey, while old oil turns black or develops white foam, indicating water contamination or pollution. Next, feel the oil: rub a drop between your fingers—good oil is viscous, while degraded oil feels thin like water. Smell is also crucial: normal oil has little odor, but if it smells sour or burnt, it means engine combustion contaminants have entered. Don’t forget to check for debris with the dipstick: pull it out and inspect—if there are metal shavings or particles, it’s a serious problem. I check every 5,000 kilometers to prevent excessive engine wear. Once, when I was younger, I neglected it, and the car started knocking, costing thousands to fix. Developing this habit saves hassle and money while extending the car’s lifespan.
