The base oil is of the naptha variety. Naphta based oil has a high aromatic content and is associated with low viscosity (VG 15 to 10). Because of their low pour point, these oils are predominantly used outdoors. They cause the usual NBR materials for seals to swell significantly, which is why elastomers with a high ACN content are required in this context. They are also associated with poor VT behaviour.
Alternative: paraffin base oil.