In daily life, the general lubricating oil is dark black, foamy and emulsified after deterioration. If it is not replaced in time, the wear and tear of parts will be accelerated, the service life of the engine will be affected, and even safety accidents will occur. Twisting with fingers, there is no thick feeling, astringency or peculiar smell, it is dark brown when dropped on the white test paper, and there is no yellow infiltration area or many black spots. So how to analyze whether the grease has deteriorated?

　　1. Oil drop trace method

　　Take a clean white filter test paper and drop a few drops of lubricating oil on the filter test paper. After the lubricating oil leaks, if there is black powder on the surface, and it feels astringent when you touch it, it means that there are many impurities in the lubricating oil. A good lube is powder-free, dry and smooth to the touch with yellow marks.

　   2. Oil flow observation method

　　Take two measuring cups, one contains the lubricating oil to be checked, and the other empty cup is placed on the table. Lift the measuring cup full of lubricating oil 30-40 cm away from the table top and tilt it to let the lubricating oil slowly flow to the empty space. In the cup, observe its flow, the oil flow of good quality lubricating oil should be slender, uniform and continuous.

　　3. Lighting method

　　On a clear day, lift with a lube check stick at a 450 angle to the horizontal. In contrast to the sunlight, observe the oil droplets of the lubricating oil. In the light, it can be clearly seen that there is no wear debris in the lubricating oil, which is good, and can continue to be used. If the wear debris is too much, it should be replaced with new oil.

　   4. Oil drop trace method

　　Take a clean white filter test paper and drop a few drops of lubricating oil on the filter test paper. After the lubricating oil leaks, if there is black powder on the surface, and it feels astringent when you touch it, it means that there are many impurities in the lubricating oil. A good lube is powder-free, dry and smooth to the touch with yellow marks.

　　5. Hand twist method

　　Twist the lubricating oil between the thumb and the index finger and grind it repeatedly. The better lubricating oil has lubricity, less wear debris and no friction. If you feel a large friction such as particles between the fingers, it indicates that the lubricating oil has lubricating properties. There are many impurities in it and can no longer be used. It should be replaced with new lubricating oil.

      According to the above method, users can judge whether the grease has deteriorated. Users who use grease can refer to the above content.