What is the normal color of car engine oil?
3 Answers
The normal color of car engine oil is light yellow. The functions of engine oil are: 1. To separate the surfaces of relatively sliding parts, thereby reducing wear; 2. To bring heat back to the oil tank and then dissipate it into the air to help the radiator cool the engine; 3. To circulate carbon deposits, sludge, and worn metal particles from engine parts back to the oil tank, and to flush away dirt generated on the working surfaces of parts through the flow of the lubricating oil. The method for changing engine oil is: 1. Use a jack to lift the vehicle, locate the drain plug and unscrew it to drain the oil; 2. After unscrewing the oil filter, place a container underneath it; 3. Replace with a new oil filter and add new engine oil.
Right after an oil change, the oil is as clear as honey with a slight amber-gold hue. After driving a thousand kilometers or so, the color darkens to a light coffee shade, which is perfectly normal. However, if the oil turns pitch black like ink and contains impurities, it indicates severe carbon buildup and needs replacement. Never wait until the oil turns milky white—that's a sign of coolant mixing in, which spells serious trouble. I check the dipstick every two months and replace the oil early if it appears too dark or lacks viscosity, as it directly affects engine longevity. Oil color reveals the internal cleanliness of the engine far more intuitively than any diagnostic tool.
Judging engine oil color is quite a skill. During my last maintenance, I specifically asked the veteran mechanic - he showed me a comparison between new and used oil. The fresh oil was a translucent golden brown, while the used oil was a darker brown but still glossy. If your engine oil is pitch black like coal, it's definitely due to prolonged use causing sludge buildup. The worst scenario is when oil turns milky white, which indicates coolant leakage mixing with the oil. When checking the dipstick, remember to wipe it on a tissue paper - uniform color means healthy oil. A friend of mine ignored his darkened oil and ended up with a seized engine, costing him 8,000 yuan for major repairs.
