What are the diagnostic methods for engine oil deterioration?
2 Answers
Diagnostic methods for engine oil deterioration are: 1. Smell test: Open the front compartment cover, pull out the dipstick, and bring it close to your nose to smell. If there is a strong sour odor, it indicates the oil has deteriorated and needs immediate replacement. 2. Finger rub test: Use the dipstick to extract a small amount of oil and rub it repeatedly between your thumb and forefinger. If you feel impurities, poor viscosity, or even a gritty sensation, the oil is in a deteriorated state and should be replaced promptly. The functions of engine oil are: 1. To reduce friction and high temperatures; 2. To minimize gas leakage and prevent contamination from external pollutants; 3. To prevent contact between water, air, acidic harmful gases, and engine components; 4. To cushion the pressure rise in the engine cylinder ports; 5. To clean away dirt generated on the working surfaces of components.
I diagnose oil degradation mainly through several common methods that can be easily done at home, which are very simple and practical. First, pull out the dipstick to check the color and texture. Normal engine oil is golden yellow or amber in color; if it turns dark black or cloudy, it may indicate degradation. Then, smell the oil—fresh oil has little to no odor, but degraded oil will have a burnt or sour stench, which is quite pungent. Next, test the viscosity: drop a bit on clean paper or rub it between your fingers. Good oil has high viscosity and feels smooth, while oil that’s too thin like water suggests severe aging. I’ve also noticed that increased engine noise or abnormal fuel consumption can signal oil issues. Oil degradation is usually caused by infrequent changes, high-temperature environments, or contamination with dust and moisture. If not addressed promptly, it can lead to engine wear and damage. I recommend checking the oil condition every 3,000 to 5,000 kilometers as part of regular maintenance—developing this habit can help avoid major repair troubles.
