The base oil is of the paraffin variety. Paraffin base oils have a low aromatic content; they are associated with good lubricating performance and favour high loads during continuous operation. They only cause materials for seals with a low acrylonitrile content (typically NBR) to swell slightly, a process which stops after a certain time. Paraffin base oils are highly viscous (around VG 22 and above).
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