How to Check if Car Engine Oil Has Deteriorated?
2 Answers
To check if car engine oil has deteriorated, follow these methods: 1. Smell Test: Open the front hood, pull out the dipstick, and bring it close to your nose. If you detect a strong sour odor, it indicates the oil has deteriorated and needs immediate replacement. 2. Rub Test: Use the dipstick to take a small amount of oil and rub it between your thumb and index finger repeatedly. If you feel impurities, poor viscosity, or even a gritty sensation, the oil has deteriorated and should be replaced promptly. 3. Color Test: Take a high-quality tissue paper and place a few drops of used oil on it. After the oil spreads, undeteriorated oil will leave no powder, feel dry and smooth to the touch, and have a clear yellow diffusion ring. Deteriorated oil will appear dark brown with impurities and should be replaced. 4. Light Test: Hold the dipstick at a 45-degree angle under light to observe the oil droplets. If you can clearly see no metal particles in the droplets, the oil is still in good condition and can be replaced later. If there are many metal particles, the oil should be replaced immediately.
I often check for oil degradation myself, so let me share my method. After parking, wait ten minutes for the oil to cool down, then pull out the engine's dipstick, wipe it clean with a cloth, reinsert it, and pull it out again to check the oil traces. Fresh oil is a clear amber color; if it turns pitch black or contains impurities like metal shavings, it's definitely degraded. I also take a sniff—normally, it shouldn't smell like anything, but a burnt or sour odor is a red flag. I rub a small drop between my fingers to test its viscosity—if it's too thin or feels gritty, something's wrong. These checks are crucial because degraded oil can damage the engine, accelerating wear, increasing fuel consumption, and causing overheating. I recommend checking monthly and always before long trips. Last time I neglected it, my car started making grinding noises, and I ended up spending money on an oil change—now it's a habit. Regular oil changes are also key—every 5,000 kilometers or six months—to keep your car in top shape.
