Diesel engine oil will absorb combustion heat and friction heat during the working process, and the oil temperature will rise, but generally it will not be higher than 90 °C. If the oil temperature is too high, there are usually the following reasons:

One model of a chemical plant was the LS25S-350HHWC Sullair air compressor. In 2015, the oil change process was carried out. After the oil change, the lubrication of the equipment did not appear abnormal. In October 2016, the customer reported that the air compressor oil had thickened and a black gel was found in the fuel tank. It is hoped that the gel will be analyzed to understand its cause and source.

If the oil temperature is too high, it will have a serious impact on the life of the oil. The hazards to the oil and hydraulic system are as follows: (1) The oil is oxidized, the viscosity is increased, and the viscous resistance is increased, which may cause the actuator to be slow and cause the system. (2) Accelerate the consumption of additives in the oil, affect the anti-oxidation, anti-rust and anti-wear properties of the oil, causing the wear of the hydraulic components of the system; (3) After the oil is oxidized, it generates acidic substances and causes corrosion to the hydraulic components. (4) Oxidation produces colloidal substances such as sludge, blocking the damper orifice and the slit valve port, etc., causing the valve member to jam. Therefore, once the hydraulic system is too hot, you need to find out the cause. For hydraulic oils affected by high temperature, they should not be used blindly. Instead, the oil should be thoroughly tested before deciding whether to continue using it according to the test results.

Most of them are used in hydraulic systems, but also in cleaning and testing. The causes of hydraulic oil pollution mainly include metal powder formed by friction, carbon residue formed by extrusion friction, sludge, moisture, and the like. The system requires relatively high oil content, preferably within the NAS9 level, and the water content is 100 PPM.

Engine oil viscosity drops are usually contaminated by fuel oil. There are many reasons for fuel oil pollution, mainly in the following aspects:

Oxidation is the main cause of deterioration of lubricating oil, and the lubricating oil is oxidized due to exposure to air during use. For mineral lubricating oils, oxidation can produce macromolecular incompetence, which usually increases the viscosity of lubricating oil. For some synthetic oils, such as polyalphaolefins, polyester synthetic oils, etc., high temperature will cause long-chain molecular cracking of base oils. It becomes a structure of small molecules, so in the initial stage of oxidation, the viscosity will decrease.