
When freshly added, car engine oil appears golden yellow. The detergents and dispersants typically added in the oil help clean off the gum films and black carbon deposits adhering to the pistons, dispersing them in the oil to reduce engine deposits. Additional information: 1. If the engine oil is black and murky, it indicates that the oil should be changed; 2. If there is no oil leakage but the oil level decreases and blue smoke appears when revving the engine, it indicates oil burning; 3. If the engine oil appears milky yellow, it indicates the presence of water in the oil. For safety, it's best to calculate oil changes based on mileage. Once a certain mileage is reached, take the car to a repair shop for maintenance to better extend the vehicle's service life.

I used to think that darker engine oil color meant it had deteriorated. Later, during , the mechanic told me that newly added engine oil is usually light yellow, somewhat like honey. It's normal for it to turn dark brown after driving 3,000-4,000 kilometers, as the oil is cleaning carbon deposits inside the engine. As long as it doesn't turn milky white or pinkish, there's no need to worry. Whenever I check the dipstick, I just keep driving if I see a uniform dark brown color. But if I notice metal shavings or impurities in the oil, even if the color looks normal, I go for an inspection immediately. Actually, regular maintenance is more important—I change my full synthetic oil every six months.

When I first bought a car, I didn't understand engine oil, but now I know its color is like a health signal for the car. Freshly changed oil is clear and transparent, and it's normal for it to turn dark like strong tea after a few thousand kilometers. As long as the color changes uniformly, it's fine. What I fear most are two abnormalities: one is milky-colored oil, indicating water has entered the engine; the other is reddish oil, which might mean transmission fluid has mixed in. During the last , I noticed silver reflective particles in the oil, and the mechanic said it's a sign of bearing wear. Now, every month when I check the dipstick, I pay special attention to the trend of color changes.


