What is the normal color of engine oil?

[StAlex]

The normal color of engine oil mainly depends on its composition. The base material of engine oil is mineral oil, and after adding various additives, the color can vary. Common colors include light yellow transparent, brown transparent, and reddish-brown transparent. New engine oil must be translucent, and when poured, it will exhibit a continuous, unbroken flow. High-quality engine oil has indistinct oil ring boundaries and appears very transparent. After some use, the oil ring color may darken slightly, and the oil ring spreads wider. For engine oil that has been used for a longer period, noticeable deposits can be seen in the middle of the oil ring, and the color becomes darker. As the engine oil continues to be used, its color will progressively darken and eventually turn black.