How to Determine if Engine Oil Needs to Be Replaced?
2 Answers
Here are the methods to determine if engine oil needs to be replaced: 1. Smell Test: Open the hood, pull out the dipstick, and smell it closely. If there is a strong sour odor, it indicates the oil has deteriorated and needs immediate replacement. This method is the simplest and most convenient, but it cannot accurately determine the extent of deterioration. 2. Finger Rub Test: Use the dipstick to take a small amount of oil and rub it repeatedly between your thumb and forefinger. If the oil feels smooth, has good lubricity, minimal debris, and no friction, it means the oil quality is still good. If you feel impurities, poor viscosity, or even a gritty sensation, the oil is deteriorating and should be replaced promptly. 3. Color Test: Take a high-quality tissue paper, drip a few drops of used oil onto it, and observe after the oil has seeped through. Good oil will leave no powder, feel dry and smooth to the touch, and have a clear yellow infiltration zone. Deteriorated oil will appear dark brownish-black with impurities, indicating it should be replaced. 4. Light Test: Hold the dipstick at a 45-degree angle under light and observe the oil droplets. If you can clearly see no debris in the droplets, the oil is still good and can be replaced later. If there is a lot of debris in the droplets, the oil should be replaced.
I used to struggle with when to change the engine oil too, until a mechanic taught me to check three things: first, pull out the dipstick to inspect the oil quality—if it's as black as cola with impurities, it's time to change; second, smell it—a sharp, burnt odor indicates severe oxidation; third, pay attention to the engine sound—if you hear metal grinding during cold starts, be alert. My driving habits also matter. Since I often drive on mountain roads, I change it every 5,000 km, but if I mostly drive slowly in the city, I can stretch it to 8,000 km. Once, I forgot to change the oil, which led to engine seizure and cost me over 4,000 RMB in repairs—a costly lesson. Now, I schedule maintenance half a month early. After all, engine oil only costs around 100 RMB, but engine repairs are unaffordable.
