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Mechanical impurities originate from external contamination during the production, storage, and use of oils, or from wear of the machinery itself; they mainly consist of sand, grit, carbon deposits, as well as some organometallic salts that are insoluble in solvents and result from additives. Its determination is carried out in accordance with GB/T 511-83 Method for the determination of mechanical impurities in petroleum products and additives (gravimetric method). The testing procedure for the mechanical impurity analyzer is as follows: Weigh 100 g of the oil sample, heat it to 70°C to 80°C, and add 2–4 times its volume of solvent. Filter through paper in a weighed empty bottle, wash the filter paper bottle with a hot solvent and weigh it again; the difference in weight before and after filtering represents the weight of mechanical impurities, from which the mass fraction of these mechanical impurities can be determined. Sediment: Total sediment refers to all inorganic and organic substances in petroleum that are insoluble in solvents such as toluene; it is one of the specification criteria for medium and heavy fuel oils. The precipitates are often mechanical impurities, or those introduced during processing, transportation, and storage. A high level of such precipitates can easily clog filters, nozzles, valves, etc., and can cause or exacerbate wear on mechanical components. The principle of measurement involves placing a certain amount of oil sample in a porous filter and continuously dripping hot solvent onto it; any components that dissolve in the solvent pass through the filter and are removed, while what remains is the precipitate that does not dissolve in the solvent. The unit of measurement is weight%. The testing standards can be found in GB/T6531 or ISO 10307.