Synthetic oil and mineral oil have no exact definition, which is commonly known as saying. API (api gravity) classifies base oils into five categories, and the third and fourth types of base oils are usually called synthetic oils. Shell's exclusive technology Xhvi belongs to the fourth category in api classification and can be called authentic synthetic oil. Among them, XHVI is the synthetic base oil of Shell's patented technology, synthetic engine oil of Mobil mainly uses PAO as raw material, and the synthetic oil of Castrol mostly uses esters as base oil. The performance of XHVI and PAO is similar, but the antioxidant performance of ester engine lubricating oil is different from the former two.
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