Precautions for Using Engine Lubricating Oil
According to data statistics, 41% of vehicle failures are caused by poor lubrication. Therefore, to fully leverage the role of high-quality lubricants, ensure reliable engine lubrication, reduce wear and failures, and extend vehicle service life, it is essential to pay attention to the selection, use, and management of engine lubricants.
1. Correctly select the type and quality grade of lubricating oil
Engine lubricating oils are divided into two types: gasoline engine lubricating oil and diesel engine lubricating oil. Gasoline engine lubricating oil and diesel engine lubricating oil differ in their performance focus, lubrication, and additive formulations, and should be used accordingly. Only those labeled as universal oils (such as SE/CC, SF/CD, etc.) can be used interchangeably within the specified grade range. Some new products may have additional instructions regarding their universal applicability, and these should be followed as recommended. For example, SG-grade gasoline engine lubricating oil can replace SF/CD or SE/CC universal lubricating oils.
When selecting the quality grade, attention should be paid to the reasonable choice based on the usage scope of each grade in the new classification. In China's latest quality classification standard for internal combustion engine lubricants, GB/17631.3-95, gasoline engine oils are divided into six grades: SC, SD, SE, SF, SG, and SH, with the QB grade (equivalent to SB grade) from the 1989 classification being abolished. Diesel engine oils are classified into CC, CD, CE, and CF-4 grades, with the CA grade from the 1989 standard being abolished. The selection of gasoline engine oil can be based on the structural characteristics and production year of the engine. Vehicles produced later, to meet environmental protection requirements, are generally equipped with additional devices in the intake and exhaust systems, making the working conditions of the lubricant more severe, thus requiring the selection of higher-quality grade lubricants. For example, gasoline engines equipped with a PCV valve (positive crankcase ventilation device) require the use of SD-grade gasoline engine oil, while engines with exhaust gas recirculation devices, such as those in the CA1091 vehicle, require SE-grade gasoline engine oil.
2. Reasonable selection of lubricating oil viscosity
Lubricating oil viscosity is a crucial property of lubricants, and selecting the appropriate viscosity is key to ensuring proper engine lubrication. If the viscosity is too high, the oil's fluidity decreases, causing friction surfaces to remain inadequately lubricated for an extended period after engine startup, which exacerbates wear during startup. Additionally, the cooling and cleaning effects of the oil on friction surfaces deteriorate. Conversely, if the viscosity is too low, it can hinder the formation of a stable oil film, reducing load-bearing capacity and compromising the sealing and protective functions for engine cylinders. Therefore, great attention must be paid to selecting the correct viscosity grade for lubricating oil. Since lubricant grades are classified based on viscosity, it is essential to choose the right grade according to the local ambient temperature.
When selecting the viscosity of lubricating oil, influenced by traditional oil usage concepts, many people mistakenly believe that higher viscosity lubricants can form a thicker oil film, thereby enhancing lubrication and reducing wear. This is a misconception that should be dispelled, because the lubricating effect of oil depends entirely on viscosity properties only within the realm of fluid lubrication. Under mixed lubrication conditions, lubrication depends not only on viscosity but also on chemical properties (oiliness), while in boundary lubrication, the lubricating effect is entirely determined by the oil's chemical properties. Therefore, under the premise of ensuring reliable lubrication, it is advisable to choose lubricating oil with as low a viscosity as possible.