设计一款车用润滑油品质检测仪。鉴于评价润滑油品质的理化指标与润滑油介电常数密切相关，而介电常数又与电容量密切相关，将PCB铜箔同轴式电容传感器、CMOS施密特触发器结合为多谐振荡器，采用易于测量的频率信号反映微小电容量，从而通过频率信号表征润滑油品质。通过STC89C2051单片机实现频率测量，采用LED指示灯对润滑油品质进行指示。对不同使用时长的润滑油品质进行检测，LED指示灯点亮个数各不相同。车用润滑油品质检测仪携带方便、使用简单、检测快速、结果可靠，能够为车用润滑油的更换提供科学依据。

A fast testing instrument for vehicle lubricating oil quality is designed and implemented, which consists of PCB coaxial capacitance sensor and CMOS Schmidt flip-flop. The capacitance signal reflecting the change of lubricating oil quality is converted into frequency signal which is easy to measure. The frequency measurement is realized by STC89C2051 single chip microcomputer, and the quality of lubricating oil is indicated by LED indicator. The test results show that the tester is easy to carry, easy to operate and use, and can detect the different qualities of engine oil well, providing a scientific basis for the replacement of vehicle lubricants.