The lubricant is dark black, foam and emulsifying. Finger rubbing, no stickiness, astringency or smell. The water droplets on the white paper are dark brown, with no yellow penetration area or a large amount of black. If not replaced in time, the wear of parts will be accelerated, the service life will be affected, and even safety accidents will occur. Therefore, it is particularly important to regularly check whether the lubricating oil is deteriorated and replace it in time.

Here are some simple identification methods:

(1) Oil flow observation method

Take two measuring cups, one containing the lubricating oil to be inspected and the other on the table. Lift the measuring cup filled with lubricating oil 30-40cm away from the desktop, tilt it, make the lubricating oil slowly flow into the empty cup, and observe its flow. The lubricating oil with good quality shall flow slender, uniform and continuous. If the oil flows fast and slowly, sometimes a large amount of oil will flow down, indicating that the lubricating oil has deteriorated.

(2) Hand twist

Twist the lubricant between the thumb and index finger and grind it repeatedly. Better lubricating oil, feel lubrication, less wear debris and no friction. If you feel a great sense of friction between your fingers, such as sand, it indicates that there are many impurities in the lubricating oil and can not be used again. Replace with new lubricating oil.

(3) Lighting method

On a sunny day, lift up the lubricating oil with a screwdriver at an angle of 45 degrees to the horizontal plane, compare it with the sunlight, observe the oil droplets, and then under the light, it can be clearly seen that there are no wear debris in the lubricating oil. It can continue to work. If there is too much wear debris, replace the lubricating oil.

(4) Oil droplet tracing method

Take a clean white filter paper and drop a few drops of oil on the filter paper. After the lubricating oil leaks, if there is black powder on the surface and the hand feels astringent, it indicates that there are many impurities in the lubricating oil. Good lubricating oil, no powder, dry and smooth feel, with yellow marks.