How to Determine if Engine Oil Needs Replacement?

[MadelineLee]

Methods to determine if engine oil needs replacement: 1. Smell Test: Pull out the dipstick and smell it closely. If there is a strong sour odor, it indicates the oil has deteriorated and should be changed. 2. Finger Rub Test: Rub the old oil between your thumb and index finger repeatedly. Good-quality oil will feel smooth, with few particles and no friction. If you feel impurities, poor viscosity, or even a gritty sensation, it should be replaced. 3. Color Test: Place a few drops of old oil on a clean white filter paper. After the oil spreads, high-quality oil will leave no powder, feel dry and smooth to the touch, and show a clear yellow diffusion ring. If the oil appears dark brown with impurities, it 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 particles in the droplets, the oil is still good. If there are many particles, it should be replaced.