This standard specifies a test method for determining the water content in lubricating grease using the distillation method. The principle involves heating and distilling the sample with an anhydrous solvent, causing the water to co-distill with the solvent. After condensation, the water separates and is measured in a receiver immiscible with the solvent, and the result is expressed as a percentage by weight. This method is suitable for distinguishing between the necessary bound water present as a structural gel solvent in lubricating grease (e.g., 1-3% water in calcium-based grease) and free water, which can degrade protective performance. It is significant for quality control in lubricating grease production and product performance evaluation. The core instrument used in actual testing is the petroleum product water content tester, typically featuring a dual or multi-unit electric heating furnace structure, allowing simultaneous testing of multiple samples. It is equipped with a straight condenser tube and a specialized receiver. Modern models also offer stepless voltage and temperature control functions to ensure a stable reflux rate of 2-4 drops per second during the distillation process.