5 ways to identify the quality of automotive oil

1. Look at the color. Normal engine oil is lighter in color. If it turns black, it means the engine oil has deteriorated. If it turns white and has foam, it means there is water in the oil and it must be replaced.

2. Look at the viscosity. Use two glass test tubes with a diameter of 5mm and a length of 200mm, and fill them with new engine oil and in-use engine oil with a height of 190mm respectively. At the same time, block the mouth of the tube with your fingers, and invert them together at the same temperature. Record the bubble rise time. If the difference between the two is 20 %, it means that the engine oil is in use and it is time to change it.

3. Look at impurities. Take 100g of the engine oil in use, pour in 200g of unleaded gasoline to dilute it, then filter it through filter paper, and dry the remaining impurities. If the mass exceeds 2g, the engine oil should be replaced.

4. Look at the oil flow. Take an appropriate amount of in-use engine oil and put it into a glass measuring cup, and then slowly pour it out. If a uniform and slender oil flow can be formed and the oil has a certain luster, it means that the engine oil has not aged and can continue to be used. Otherwise, it should be replaced.

5. Look at oil spots. Put a drop of used engine oil on the white filter paper and observe its changes. If there are only small black spots with a lighter color in the center of the oil stain, and the surrounding yellow traces are larger, it means that the engine oil can continue to be used. If the black spots are larger in size and darker in color, it means that the engine oil has aged and deteriorated and should be replaced.