What is the standard for scrapping lubricating oil?

What is the scrap standard for lubricating oil? How many people know about this issue? Let's analyze this issue together today.

1. Viscosity: 

If the viscosity of the engine oil is too high, the low-temperature starting and pumping performance will deteriorate, and the circulating cooling effect will decrease, which will hurt the friction and wear of the engine. If the viscosity is too low, the engine oil capacity will decrease, and the wear will also increase. 

Therefore, most of the viscosity scrap indicators are stipulated as the range of kinematic viscosity change at 100°C not exceeding 20%-25%, and some regulations do not exceed the SAE viscosity grade of the oil.

2. Insoluble matter: 

The pollution of the engine oil can be roughly judged from the insoluble matter of n-pentane and benzene, and the regulations on the limit content of insoluble matter in the engine oil are quite different.

3. Water: 

Since the operating temperature range of automobile engines is very wide, it is inevitable that a small amount of condensed water enters the engine oil, which may be a sign of cooling pump leakage. Therefore, the maximum water value of the used engine oil is generally set at 0.5%. Exceeding this value indicates that there may be free water.

4. Neutralization value: 

The engine parts most susceptible to acid corrosion are bearings. Tin or lead-based bus alloys have good corrosion resistance. Most diesel engine bearings are copper-lead alloys that are susceptible to corrosion. 

The original scrap standard for diesel engine oil acid value was set at 0.5. After using oil containing additives, some metal salt additives react chemically with potassium hydroxide, and the acid value of the new oil sometimes far exceeds the 0.5 regulation. 

Therefore, the acid value of used oil should be set to a maximum limit based on the changes in additives and acid value in the oil, or only the minimum depreciation of used oil should be set without controlling the acid value.

5. Flash point and fuel dilution: 

These two indicators are interrelated and both significantly affect the viscosity of the oil. Therefore, it is appropriate to consider the viscosity together as a scrap indicator.