At What Color Should Engine Oil Be Replaced?
2 Answers
Engine oil color primarily depends on its composition. Generally, car owners decide whether to replace it based on the oil's usage condition. Below are specific methods: 1. Take a drop of engine oil and place it on test paper, observing the oil's spreading area. 2. Good engine oil has indistinct oil ring boundaries and appears very transparent; oil that has been used for a while will have slightly darker oil rings and wider diffusion; oil used for a longer time will show obvious sediment in the middle of the oil ring with a darker color; as engine oil continues to be used, its color will gradually darken and eventually turn black.
I've been driving for over a decade, and judging when to change engine oil based on color isn't that straightforward. Fresh oil is clean and translucent like honey—it's normal for it to turn black over time as it collects contaminants, but darkness alone doesn't always demand an immediate change. If the oil appears deeply black yet free of particles, it might still have some life left. However, if you notice a milky white hue or metal flakes, that signals serious issues like coolant mixing or engine wear—pull over and inspect immediately. Don't rely solely on color; track your mileage—I typically change mine every 8,000 km or so, even sooner in cold winters to prevent thickening. Make it a habit to check the dipstick monthly to monitor color shifts; this simple trick proves surprisingly effective.
